688 lines
47 KiB
Plaintext
688 lines
47 KiB
Plaintext
.he CHAPTER 7 CORBIN HANDBOOK AND CATALOG NO. 7, PAGE #.op
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SOME SPECIFIC BULLETS AND HOW TO MAKE THEM
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I've already written seven books and my editors tell me I have
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over 400 articles in print, describing the various things you can do
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with swaging. It would be ridiculous to try and explain every possible
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bullet style in this book -- you'd need a flat-bed truck to haul it out
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and a crane to flip the pages!
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Rather than that, I will try to explain how each of several
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examples of bullets can be made, selecting very simple and very exotic
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kinds of bullets, including features that shooters find exciting, and
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designs that appear difficult or impossible until you have seen how
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simple swaging makes it. From these few examples, you should begin to
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gain an understanding of the process and how much more you can do with
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it.
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HOLLOW BASE TARGET PISTOL WADCUTTERS
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Lead wadcutters with hollow base can be made in a reloading press
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in the calibers from .25 ACP to .357/.38, up to .458 caliber in the
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Mity Mite, and up to .75 caliber in the Hydro-press. The reloading
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press makes as accurate a bullet in regard to diameter control, but for
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superior weight control, you should use the Mity Mite or larger swaging
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presses.
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Select either a core seating die or a lead semi-wadcutter die.
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The core seating die should be ordered with a wadcutter nose external
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punch, and a hollow base internal punch. So should the LSWC-1 die, if
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you wish to use that one. (I would -- it isn't available in the
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reloading press system, however.)
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Prepare your lead cores by either casting them in the Corbin 4-
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cavity adjustable weight core mould, or by cutting uniform length
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pieces from a spool of lead wire. Specific instructions are found with
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the tools or in other sections of this book. More detailed information
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can be found in the book "Rediscover Swaging".
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To establish the proper weight of core, make one and put it in a
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scale pan. Then adjust the next few until you get what you want. If
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you plan to use a core seating die (CS-1) without a core swage (CSW-1),
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then what you put in is what you will get out in regard to weight.
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This is the case with reloading press die sets, since there is no core
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swage for them. It isn't necessarily a bad situation. I shot a lot of
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good groups when I was in the Navy using bullets that had 3-5 grains
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variation in my trusty .45 Colt Government pistol.
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If you do use the Mity Mite or other special swage press, and plan
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to use a core swage or the all-in-one lead semi-wadcutter die (LSWC-1),
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then make the cores from 2 to 5 grains heavier than you want in the
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bullet. That gives you some extra lead to extrude along with any
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variation in weight.
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Lubricate the core by one of two methods. If you want a clean
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lead bullet with no lubrication, use Corbin Swage Lube on your finger
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tip and thumb, and just give each core a little rotation between them
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as you pick them up to put them in the die. It's simple and natural,
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no big deal. Let the benchrest rifle fanatics worry about measuring
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out lube with a hypodermic needle on a special stamp pad: it won't
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make any practical difference in where the bullet lands.
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The other method is for placing a wax jacket on the bullet itself.
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Instead of lube grooves which apply a little band of lube and let the
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rest of the bullet scrape along the bare metal contact with your bore,
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the whole surface of the bullet can be covered by a thin, hard film of
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high temperature wax.
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The product that does this is Corbin Dip Lube. Some call it
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"Liquid Jacket". That's what it acts like. You dip the core in a
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small container and put it wet into the swage die. Then apply
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pressure, swage the bullet, and it comes out nearly dry. Let it cure
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for fifteen minutes, and you are ready to load and shoot it! No
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sizing, no lubricating, and more lube contacts the bore than if you had
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it plastered with conventional drag-producing grooves.
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Drawback? Alox-beeswax lube works at somewhat higher velocity
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levels than Corbin Dip Lube. If you are pushing the bullets toward
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magnum speeds, you may be in for some leading. On the other hand, that
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is what Corbin bullet jackets are made to prevent. From 1,200 fps
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down, I have had excellent results with the Dip Lube. Many commercial
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firms purchase it in gallon lots for their bullets, so I know that it
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works as well for their customers. Any lead bullets can produce
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leading in some guns and with some loads, of course. I certainly do
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not claim this product is the best lubricant made, but it is one of the
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most convenient and easily used, especially with swaged bullets.
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Before swaging the bullets, you may want to know how to put the
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dies in the press. For the Hydro-press, you should have the book
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"Power Swaging" at hand. You need it, period. Without it you will
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break dies. For the Mity Mite, a brief reading of the instruction
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sheet that comes with the press and dies should make the installation
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and operation fairly clear. For the reloading press, ditto.
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But here's a quick run-down: the Mity Mite die goes into the ram
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of the Mity Mite press. The ram is the steel cylinder that moves in
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and out of the press frame when you pull on the handle. It has a 5/8-
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24 TPI thread in the working end, and the handle forks attached to the
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other end.
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There are two punches with the die (each and every die has two
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punches that are required to operate it, except for draw dies). Lead
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tip dies come with one punch, but use your existing point forming die
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bottom punch. We are not going to be using those dies now. The
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reloading press has an internal punch captive inside the black,
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threaded adapter body. It's external punch slips into the press ram,
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and the die screws into the pressd head like any reloading press die.
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In the reloading press, you would be using the CS-1-R core seating
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die, and you would have the hollow base internal punch inside the die.
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If you wanted to install this punch (because the die normally comes
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with a flat base internal punch, and you order the other base shapes as
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optional punches), you would unscrew the die insert from the bottom of
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the die and then pull the original flat base punch straight out of the
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top of the die insert. You would clean the new punch, and press it
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gently into the top of the die insert, then screw the die and punch
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together back into the adapter body.
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In the Mity Mite press, you would see that the die has threads on
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one end and a venturi (funnel-shaped) opening at the other end. This
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venturi opening helps align the external punch. The threaded end
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should have a steel cylinder with two diameters protruding from it.
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This is the head and tail of the internal punch. The tail is about
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0.312 inches in diameter, and the head (right next to it) is about 0.50
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inches in diameter. The rest of the punch is the same size, minus a
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tad, as the die bore. It is a diamond-lapped sliding fit.
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If you want to change the base shape, you slide this punch out of
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the die, clean the new one carefully of all grit and dust, and slide it
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carefully into the die from the threaded end. Flat base, cup base,
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hollow base, and dish base shapes can all be made this way. Bevel base
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can be simulated but remember that all end shapes which are formed by
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pressing against a punch will have some degree of shoulder or step
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where the edge of the punch contacts the bullet. A true bevel base is
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not made in this simple kind of die.
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Screw the die into the press by hand. In the Mity Mite, screw it
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in all the way. Don't use tools. Hand-tight is tight enough. Don't
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confuse the swage die, which is about 3/4-inch in diameter, with the
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black threaded floating punch holder (FPH-1-M) in the press head! Many
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people think the punch holder is the die, because it looks like a
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reloading press die.
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The external punch is held in the punch holder. In a previous
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chapter this was covered with photos and detailed description. The hex
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bushing unscrews from the end of the FPH-1. Inside is a collar or
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bushing that slips over the punch. (If the punch is smaller than .375
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diameter -- if not, the punch already has the bushing and hex bushing
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assembled to it. Just remove the one in the FPH-1 and set it aside,
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take out the round rocker bushing but leave in the solid rocker
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button. Install the punch as one unit.)
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Assemble the round rocker bushing and then the hex bushing over
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the external punch. If you have any doubt as to what part is the
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external punch, look for the one part that does NOT fit into the die
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full length so that it comes to the mouth of the die and fills it
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completely from end to end with some left over!
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The die is the round steel cylinder with the hole through it. You
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can see through it if you pull out the internal punch. The internal
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punch will NOT fit into the floating punch holder properly. It has a
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tail section that keeps it from fitting. The head of the internal punch
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and the head of the external punch are the same diameter, but the
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external punch has no projection or tail section. It steps down from
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the head (about .50 inches diameter) to the shank (about 0.36 inches
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diameter) to a section that is just below bullet diameter, having a
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portion that is closely fitted to the die bore.
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The punch should be held finger-tight in the floating punch holder
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at this point. The adjustment of the punch holder is made by putting
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one of the lubricated cores into the die mouth, and carefully moving
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the ram forward so that the external punch can be aligned with the die
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and moved into it. The object now is to adjust the punch holder so
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that the press handle can be moved to the point where the die is
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forward as far as it can go. If the punch and holder stops the ram
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from going forward now, back off the punch holder. If the punch
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doesn't contact anything yet, that's fine. Just get it into the die.
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Make sure that the ram is capable of going as far forward as
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possible, unlimited by coming against the punch or holder. No pressure
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should be generated, no particular force required. The weight of the
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handle should be more than sufficient to move the ram forward all the
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way. Have you got that adjustment made? Make sure the ram is free to
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move back and forth on both sides of its foremost extension. You can
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tell if it is right, because the pivot pin that holds the ram to the
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press handle will line up on the same plane as the bolt that holds the
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handle to the two links.
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Now, holding the handle so that the ram is at the furthest
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position forward, screw the floating punch holder toward the ram. Keep
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turning it by hand until the punch contacts your lead core and you can
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no longer turn the punch holder by hand. If, at this point, you are
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able to screw the punch completely into the die and the die face comes
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up against the hex bushing on the punch holder, something is not right.
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The possibility is that you didn't have enough lead core for the
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set the way it is. The cure is to obtain a hardened steel bushing to
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slip over the tail of the internal punch, extending it forward. Do NOT
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try to machine or modify the external punch or die to cure thholder by hand. If, at this point, you are
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able to screw the punch completely into the die and the die face comes
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up against the hex bushing on the punch holder, something is not right.
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The possibility is that you didn't have enough lead core for the
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set the way it is. The cure is to obtain a hardened steel bushing to
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slip over the tail of the internal punch, extending it forward. Do NOT
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try to machine or modify the external punch or die to cure thward again.
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Did any lead come out the bleed holes in the side of the LSWC-1 die?
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Or, did you feel a rather sudden increase in the resistance in the CS-1
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die? Back off the ram, eject the bullet, and see if it is nicely
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filled out. See if it stays in the die, or if it comes back out with
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the punch.
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Normally, the bullet will stay in the die even if it is somewhat
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undersized at this point. Jacketed bullets often come out with the
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external punch until enough pressure has been applied to expand them to
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die diameter. When you run the ram all the way back, the internal
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punch comes up against the stop pin in the back of the press and pushes
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the bullet out by holding the internal punch still while the die
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continues to move back with the ram.
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If the bullet is poorly formed, adjust the punch holder a fraction
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of a turn forward and try another core. When you get it right, the
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bullet will be properly formed and will measure the correct diameter
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from one end to the other. The internal punch will have formed a deep
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hollow cavity and the external punch will have transferred its nose
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shape to the end of the bullet (in this case, a wadcutter nose).
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If you have voids or unfilled edges on the bullet, then you might
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have a bit too much lube. Wipe the lube off the external punch and try
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another core without so much lube applied. If that still doesn't come
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out well, adjust the punch holder slightly forward again. But do NOT
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keep adjusting the holder forward until you feel an extreme resistance.
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One hand force is all you should ever need to apply. If it feels like
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you should be using both hands, something is wrong and you may be on
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the verge of breaking your die. Stop and find out what is wrong.
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If the lead is too hard, this can be a serious problem. Hard lead
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does not flow or swage very well. Soft lead swages very nicely. The
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pressure required to swage even a 3% antimonial alloy of lead is at
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least double that of pure lead. When you first start, it may be hard
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to judge how much pressure is enough. The press is so powerful that a
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very light pressure on the handle produces a very great force on the
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ram. With calibers in the .375-inch range and up, you can break the
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die without seeming to apply undue effort, so be careful to stop
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applying force or adjusting the punch holder forward as soon as you
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reach the point where the bullet begins to form nicely.
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With a little pressure on the ram, while swaging a bullet, cinch
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the hex bushing on the punch holder up snugly by hand. This keeps the
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punch aligned with the die, so you don't have to do more than check it
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from time to time. Swage all your bullets with the punch holder set at
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this position and the locking nut secured against the face of the press
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head. If you want to repeat this setting soon, lock down the set screw
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on the punch holder. Having several punch holders gives you quick
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repeatability by leaving each punch in its own holder with pre-set lock
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nut.
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Now, back to the reloading press. The adjustment is exactly the
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same, except that you put the external punch in the slotted ram, and
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adjust the die downward toward the punch, while the punch is raised to
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the topmost position of the ram. It is important that you realize that
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the furthest extension of the ram is what controls consistent results.
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If you swage by feel entirely, you may get widely changing weights.
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Use feel to judge whether or not a core is a great deal lighter or
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heavier as you approach the top of the stroke.
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Do NOT continue to press if you meet resistance before you
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normally did on similar bullets during a run. You will probably swage
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a heavier than usual bullet, at best, and at worst you may break the
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die or mash the punch flat. Set aside any cores that either developed
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less or more resistance to swaging than your usual bullet during any
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given run. Those are light or heavy cores. They can be used for some
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other weight, or melted down for a cast core.
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We have covered a lot of elementary material here. Refer to this
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basic bullet and adjustment procedure for just about any other die.
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The concept is the same: approach the right adjustment from the loose
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side, where you have no pressure, and increase it in small bits until
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you achieve the desired result without exceeding moderate efforts on
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the handle. It is a lot like experimenting with a new powder charge:
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build the load in small increments and watch for signs of pressure.
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Here we are dealing with pressures that could destroy a rifle when they
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are normal. But they don't contain much total energy, so no parts fly
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around when a die breaks. You hear a crack, and you see one in the
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die. That's about it. With just reasonable care, you'll never know
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what a broken die sounds like.
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For the rest of the bullet styles, I will give only a brief
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description of the process, detailing only the unusual aspects of
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making the bullet. Please remember the basic rules: swage dies
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increase diameter, never reduce it. Lubricant is required for every
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swaging operation (I won't keep mentioning it). The punch must fit
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easily into the die, or it is the wrong one to use. The force you feel
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should on the handle should be mild, never requiring double-handed
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effort. And while you can experiment, do get a good understanding of
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the basic operations for each die first.
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HOLLOW POINT JACKETED HANDGUN BULLETS
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The hollow point is made during core seating. Instead of using a
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flat faced punch to push the core into the jacket (in the core seating
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die), you need to order the optional hollow point external punch. This
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punch has a conical probe on the face, which presses down into the lead
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core and forms a cavity at the same time that the lead is pressurized
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to move the jacket walls out and meet the die.
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A more uniform hollow point can be made if you first seat the lead
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core with a flat punch, then change to a hollow point to form the
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cavity. This step is for the perfectionist, and may be unnecessary
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even then, depending on how deep the lead seats in the jacket and other
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factors.
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In any press, this operation takes place as a result of using a
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hollow point punch during the core seating operation. The dies
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themselves are the same, regardless of whether you select a hollow
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point or a soft point, an open tip or a full jacket. In a single core
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seating die, for making semi-wadcutter or wadcutter hollow points, you
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can use the HP punch either before or after using another nose punch.
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The key to successful use of more than one punch on the same
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bullet is to realize that you do not have to press the punch all the
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way into the die. Using a portion of the possible extension into the
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die and lead gives you almost total control of how deep and how big the
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cavity will be. Whether you swage the HP first or use another punch,
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such as a Keith nose punch, first, determines the cavity size and the
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shape of the bullet.
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A Keith punch and a hollow point punch can produce a wide range of
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shapes, including a simulated round nose! Experiment with various
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insertion depths. In other words, adjust one punch to go in further
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and the other one to stop short of going in all the way. Using both to
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the full extent possible only means that the bullet will be primarily
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formed by the last punch you press against the lead. Whichever punch
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is pushed in hardest and further against the lead is the one that gives
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the bullet most of its final shape.
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If you use a point forming die, then of course you do not need to
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experiment with semi-wadcutter nose punches. The point forming die
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will shape up the ogive for you. It will also smoothly close the
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hollow point to a more long and narrow shape, depending on how far into
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the point forming die you wish to push the bullet. If you adjust the
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press and die so that you just barely push the bullet into the point
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forming die, then you will have a very large hollow point.
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On the other hand, if you push the bullet into the die as far and
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as hard as you reasonably can, you may well close the hollow point
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completely. This can produce an unusual result: you can fill the
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hollow point cavity with a fluid or powder, or a steel ball, and then
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cause the end of the bullet to roll over this material and trap it in
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the cavity. If the hollow point is much deeper than the ogive length,
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a good portion of the cavity will remain at its original size while the
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part toward the end of the bullet becomes more narrow.
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This means you can make hollow point
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completely. This can produce an unusual result: you can fill the
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hollow point cavity with a fluid or powder, or a steel ball, and then
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cause the end of the bullet to roll over this material and trap it in
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the cavity. If the hollow point is much deeper than the ogive length,
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a good portion of the cavity will remain at its original size while the
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part toward the end of the bullet becomes more narrow.
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This means you can make th
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your more experimental designs.
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BOATTAIL HANDGUN BULLETS
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With a long shanked rifle-style bullet, a special set of dies is
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required to manufacture a good boattail base. At Corbin, we make the
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rebated boattail base, popularized by the fine Lapua match bullets.
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But in a short, stubby handgun bullet, it is easy to make a rebated or
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a regular boattail using only a special punch (and not really all that
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special).
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Usually, it's necessary to seat a lead core in the jacket using a
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core seating die. The die is sealed on both ends by punches, so
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pressure can be built up inside the jacket to expand it like a balloon.
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If you turn the jacket over so the closed end is toward to top of the
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cavity in a point forming die, then you can apply a fair amount of
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pressure inside the jacket with an external punch that fits down into
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the jacket. The fit must be close, to keep the pressure from extruding
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lead around the punch. But it is practical and works well.
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If you put a core inside a handgun jacket, then use a punch
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(ordered as an open tip core seating external punch) that fits into the
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jacket to press against the core, and put the assembly into your point
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forming die (base first), you will produce a full jacket, open base
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handgun bullet.
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Should you have a truncated conical point forming die, rather than
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a round nose shape, you will actually have what could be considered
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either a nose or a boattail base! To use it as a base, eject the
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bullet and change the external punch to a regular Keith nose punch that
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fits into the point forming die by hand. (Remember, in your
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experiments, to try each punch by hand first -- you don't want to fit
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the punch to the die permanently!)
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Now, with the Keith nose punch installed in die, rather than
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a round nose shape, you will actually have what could be considered
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either a nose or a boattail base! To use it as a base, eject the
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bullet and change the external punch to a regular Keith nose punch that
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fits into the point forming die by hand. (Remember, in your
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experiments, to try each punch by hand first -- you don't want to fit
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the punch to the die permanently!)
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Now, with the Keith nose punch installed in point
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(depending on how much lead you moved forward) TC nose, a short shank,
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and a rebated boattail base -- what a combination! But give it a try.
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You can load it either direction. I like to make these bullets with
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about one caliber length of straight shank. That usually means a
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bullet with one of the longer jackets and toward the heavier end of the
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weight scale. But as you can see from some of the tests in the
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magazines (one of which is reproduced in the Corbin Technical
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Bulletins) this design can result in a 40% improvement in ballistic
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coefficient and as good or better accuracy than conventional shapes!
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SHOTGUN SLUGS WITH ATTACHED BASE WADS
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This is a task for the Hydro-press system. There are many
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possible kinds of highly accurate slugs you can produce. One is a slug
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that fits inside the Winchester Red Wad, and is thus made slightly
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under normal diameter to use the sabot effect of the standard plastic
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wad. Another is the slug with wad attached to it. This operation is
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quite simple. A die set can even be produced to stamp out excellent
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wads from various materials. The details of operating the press are in
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the book "Power Swaging".
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I will just outline the process here. The wad is made with a hole
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through the center. The hole is precisely centered as a result of the
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die-forming process. The pre-swaged core and wad are put into a die
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with a nose cavity punch in the die, and a base punch having a slight
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depression in the face, like a smooth rivet head, follows the wad into
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the swage die. A core seating or lead semi-wadcutter type die is used.
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As pressure is applied, the lead flows up into the nose punch
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cavity and forms any desired shape of nose. Usually a conical flat tip
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or a domed shape is made. The lead also presses hard against the wad,
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and finds a pressure escape through the hole in the middle of the wad.
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The lead flows through this hole, and fills the cavity in the head of
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the punch that is backing up the wad.
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The wad is compressed under tons of pressure, and so is the lead.
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The lead extrusion through the hole in the wad forms a perfect rivet
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head on the other side of the hole. When the bullet is ejected, you
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have a lead slug firmly attached to the wad, which now tries to spring
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back to original size and keeps pressure on the base of the slug.
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Another unique twist on this is to form a hollow base cavity with
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a post in the middle, and with a hole in the middle of the post that
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will take the threads of a number six or eight metal screw. It might
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seem very complex, but in reality all you have to do is imagine a punch
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having a mirror image of this cavity and post and hole formed into the
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steel face. The reamer and polishing work required is, of course,
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somewhat expensive. But it is well within reason for anyone who wishes
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to manufacture a unique kind of slug.
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The idea is to shift the weight forward, maintain a longer bearing
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surface for alignment, without having a massive weight, and provide
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solid support in the middle of the cavity so that the wad is not blown
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into the cavity upon firing. The screw attaches the wad to the post.
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It might even be possible to fill the cavity with cornstarch and then
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swage the wad to the slug, but this has not yet been tried (maybe by
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the time this book has been out a year, it will be common).
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PRECISION AIRGUN PELLETS
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Airgun pellets are really no different from any other hollow base
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semi-wadcutter bullet. The dies have smaller punches and cavities than
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most calibers. Corbin makes .20, .14, .17, .224, or anything else you
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like. Diameter is critical. Rather than the waisted design, these are
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like a precision handgun bullet in minature.
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They have a deep hollow cavity and thin skirts to give a good
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seal, and they usually are made slightly smaller than a waisted pellet
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so that the bore friction is reduced. Swaged with a Dip Lube coating,
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they provide good lubrication that is consistent and dry in all
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temperatures. The nose can be conical or of the Keith style with
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equally good results. Such pellets in .2235" diameter make excellent
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indoor practice bullets or mouse shooters in a conventional centerfire
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rifle used with a primer only.
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There are complex ways to swage the waisted pellet, but it isn't
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usually worth the effort compared to the results you get with the
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simple single die method in either reloading press or Mity Mite. In
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the reloading press, only a .22 pellet is offered, unless a run of at
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least 100 dies is ordered (for resale). But in the Mity Mite, you can
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have anything you wish.
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PLASTIC TIP RIFLE BULLETS
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Several of the common plastic rod materials swage nicely to form
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lead tip replacements in any conventional rifle caliber. Nylon,
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polyethylene, and other "soft" plastics that can be shaped by pressure
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and retain that shape after pressure is removed make nice tips for your
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hunting bullets. The idea of the plastic tip predates the current
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Nosler design by many years, as seen in the early Norma nylon tips and
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in home-swaged bullets using Nylon tubeless tire patches (plugs) in
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stark black or white.
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The FBI once contacted Corbin about making Nylon bullets for
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handgun use in an indoor training facility. The idea came about
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because a conventional Speer Nylon bullet had a sharp shoulder that
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prevented the use of speed loaders. When these bullets were re-swaged
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in a simple Corbin point forming die, right off the shelf, they
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acquired a more bullet-like profile and worked in the conventional
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speed loader.
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A side benefit turned out to be that the agency could reload these
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plastic bullets seemingly without end, after reswaging to remove the
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rifling and other impact marks. I have one left in my collection that
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was shot and reloaded and reswaged over 25 times, and it could still go
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on without any apparent change.
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Nylon rod can be obtained from most plastic suppliers. It can be
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cut to short lengths in a lathe or bandsaw. The bullet is made in the
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same way as any open tip design, by seating the lead down inside the
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jacket with a punch which fits into the jacket. But before the point
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is formed, the short piece of Nylon is placed inside the jacket. The
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diameter should be close to the jacket ID.
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When the point is formed the jacket and Nylon plug smoothly swage
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into one profile. The ogive locks the plastic in place (it crimps into
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the material since the plug is larger inside than at the external tip).
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FRAGMENTING BULLETS
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Bullet swagers have been making their own fragmenting defense
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bullets for years. It is extremely simple. Just dipper a charge of
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number twelve lead shot into a jacket, and seat the shot like it was a
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solid core. Press a bit of soft wax or a thin cardboard wad over the
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shot. A wad can be made in a regular swage die of smaller caliber by
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putting a bit of cardboard between the punch and die and pushing
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through it.
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Then, form the ogive in a point forming die. To increase the
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fragmenting effect, first roll or tumble a quantity of shot with a
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little dab of Corbin Swage Lube. This lube keeps the shot from
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sticking together -- it may appear solid when you swage it, but on
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impact it break up nicely.
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HYPERSPEED BULLETS
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What would you call a bullet that goes 2000 fps from a snubby .38
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Special? Impossible? No, you can develop an ultra-light bullet in any
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caliber and then find a fast-burning charge of the right powder to
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propel it at unbelievable speed. Some of the effects are dazzling.
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Here is how you retain enough bearing for a semblence of accuracy
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and still keep the bullet weight down: use cornstarch as a core!
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The secret is out...but only bullet swagers know about it.
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Cornstarch swages under high pressure to form a sort of hard plastic
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material that is much lighter than any conventional jacket filling, yet
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expands the jacket as well as lead under swaging pressures.
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Because of the low density of the material, even when swaged to a
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plastic state, you can make a regular length bullet that seats and
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balances as it should, yet has very low inertia. The sectional density
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is very low, which means it doesn't penetrate very far and it also
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doesn't fly very far before losing its speed. Those can be good
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features in a defense bullet used in populated areas.
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When you top the cornstarch with a small amount of lead, you can
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produce a method of delivering a devastating high velocity projectile
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without nearly as much danger to people behind the intended target.
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Make the filling out of swaged lead shot of small diameter, rolled with
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Corbin Swage Lube, and you have just produced a superior fragmenting
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bullet with ultra-high velocity. You need nothing special to do all
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this, except the right punch to fit into the jacket at the depth where
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you want to swage the material.
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PARTITION STYLE HANDGUN OR RIFLE BULLETS
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Putting a partition across the middle of a bullet is as easy as
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telescoping two different diameters of jackets together. This is
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covered in some detail in the book "Rediscover Swaging". Basically,
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the inside jacket is of smaller caliber and is about half the length of
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the outside jacket. When jackets do not exist ready-made to fit this
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way, a Corbin JRD-1 draw die can turn some available jacket into the
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right size.
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In the Hydro-press system, it is possible to make partitions by
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folding and pressure-welding the actual jacket wall material into a
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band across the jacket at any desired point. Copper tubing is normally
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selected, so you have both the benefit of the soft copper tubing and
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the partition effect. If you want to go one further, add Corbin Core
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Bond and a little heat, and you have a bonded core, partitioned, copper
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tube bullet -- something none of the famous firms who are known for
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making one of these features apiece have managed to combine.
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PENETRATOR CORE OR LIQUID FILLED CAVITY BULLETS
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I group these two styles because they are made the same way. A
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set of special punches is made to seat a very light core in the bottom
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of the jacket. One punch seats the core, and the other puts a center
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in the core. Then a long hollow point punch slips down into the
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jacket, finds the center, and starts extruding lead up along the punch
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sides. Plenty of good lube is required on the punch.
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The punch is withdrawn, leaving a long, deep cavity precisely
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centered in a lead sheath inside the jacket. A carbide, uranium or
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other heavy metal core can be placed in this cavity. It works best if
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the insert material is slightly larger than the cavity for a gentle
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press fit. A punch can also be made to do this.
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Corbin does not provide these heavy metal cores. Most of the
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people who do this work are able to obtain their own from defense
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agencies or suppliers. Such bullets are usually made for special
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projects within the military and are discussed here only to show the
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possibilities. Liquid filling for the same cavity can easiy be
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substituted. A lead ball is placed in the end of the cavity to help
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seal it, and then the bullet is put into a point forming die and the
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ogive shape extrudes lead over the widest part of the ball and locks
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the assembly together.
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ULTRA PRECISION BENCHREST RIFLE BULLETS
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The quality of the bullets you can make in a typical Corbin swage
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die for the Mity Mite or Hydro-press will equal or exceed that of any
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bullet made today. You do not need to pay thousands of dollars for
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special "benchrest" quality. The best quality that money can buy comes
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far less dear than some folks imagine possible.
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On the other hand, I do not recommend the die sets that we
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manufacture for use in a reloading press as benchrest bullet dies.
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They are good dies, and have often been used to make match-winning
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bullets. But the system does not lend itself to what I would call the
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ultimate control over the bullet weight and style.
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Reloading press dies are made to work in a press that was not
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designed specifically for bullet swaging. Corbin Mity Mite and Hydro-
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press dies were designed along with the press, without having to
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consider factors necessary for reloading. The Hydro-press and the Mega
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Mite press both handle reloading as a side benefit, not as a primary
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goal that might restrict optimum design for bullet making.
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Alignment, sensitivity of control ("feel", if you like), balance
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of the forces that tend to produce ram torque, amount of press head
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movement under stress, maximum leverage potential, and other factors
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from how ejection is handled to where the top of the ram comes to rest
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in relation to the press head, are all optimized for bullet making the
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the special swaging presses. These things simply are not there, in a
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reloading press. It doesn't matter how big or strong or expensive the
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press is: if it was made primarily for reloading ammo, it wasn't
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optimized for making bullets.
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I have had a few perverse clients shoot winning matches with
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bullets made in our standard reloading press dies, and they enjoyed
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telling their fellow shooters (who had spent thousands of dollars, in
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some cases, for the "right" benchrest equipment) how little their
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equipment cost (usually under $250 for everything -- dies alone cost
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about $160). But while it can be done, I certainly feel that you are
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better advised to use equipment made with all the benefits of the
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special swaging press in mind.
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There are two secrets to making benchrest bullets. First, the
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jackets themselves must be very concentric and should be weighed so
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that you can cull out any over or under a nominal value. Different
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weight by itself has little effect on the bullet path, within a factor
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of from 1 to 2 percent of the total bullet weight. (Calculate the drop
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difference and you will see that one-hole groups at 100 yards are still
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possible with bullets that weigh plus or minus half a grain in a 55
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grain .224 caliber, or bullets that have 1.5 grain variation in a 150
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grain .308 caliber).
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The problem with weight variation is that it can be caused by a
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thicker base, thicker walls, or even a difference in wall thickness
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from one side to the other. If it is merely a bit longer jacket, it
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won't have much effect. And the heavier or lighter jackets, by
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themselves, do not cause bad groups. It is a mixture of different
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jackets that can throw off the group size. A heavier or lighter wall
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is not bad, it just can't be used with something different in a
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benchrest match.
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The next secret is consistency in the method of making the
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bullets. The little rituals and weird theories about what makes a
|
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bullet shoot are a lot of fun for the people who believe in them, and
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even if they make little sense to rational people, I see no harm in
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following the latest fad in regard to many of the rituals. But for a
|
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person who is mainly interested in fact, and wants to see what really
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does and does not make a difference, it doesn't take too long to see
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that a machine rest in an indoor tunnel easily proves that consistency
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makes more difference than any specific method.
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In other words, whatever you do in regard to how you apply your
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lubricant, whether or not you "rest" the cores overnight before
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swaging, or whether or not you spin and weigh each bullet in some
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questionable fixture or tool made to point up some mysterious accuracy
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factor, the real effects will come from doing things the same way each
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time, so all the bullets do indeed come out looking and shooting the
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same way.
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Some of these rituals help produce a more consistent bullet, often
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for reasons not entirely related to the goal that the shooter feels he
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is trying to reach by that ritual. Benchrest shooting originally
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brought a great many serious benefits and pointed out errors in how
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bullets were being made during the 1940's and 50's. To some extent, a
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level of mystique and fraternalism has moved into the place that used
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to be held by serious investigation, with the quirks of the latest
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winner being slavishly repeated by next year's would-be winners.
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But this is true in all competitive sports. Winning matches does
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not necessarily make the shooter an expert on every aspect of the tools
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and equipment used to win. Sometimes a good deal of winning is
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attitude and practice, especially when equipment differences become
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very slight at the top levels. All of this is merely to point out that
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making benchrest quality bullets is not necessarily the exclusive realm
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of a white-bearded wizzard who knows cosmic secrets which you, mere
|
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mortal, can hardly be expected to understand.
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As a matter of fact, nearly anyone with a reasonably good set of
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dies and careful attention to what he is doing can turn out bullets
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capable of one-hole groups. Then it is up to the rest of the system,
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including the handload and the gun, the shooter and the fates that blow
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the winds, to let that one-hole group appear on any given day.
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This information doesn't play well with those who would like to
|
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have you believe there are dark secrets beyond your reach, which only
|
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certain people (who happen to have something they might -- hold your
|
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breath! -- be persuaded to sell you) have in their posession. But you
|
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can prove it to yourself, and to anyone else who doesn't have too big a
|
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stake in keeping it quiet! There is no fundamental difference in the
|
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potential quality of a .458 bullet, a .600 Nitro bullet, or a .224
|
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benchrest bullet made by the process of swaging outlined here.
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All swaged bullets made by hand on good equipment, using
|
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consistent components, can be made carefully and well. They can all be
|
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benchrest bullets of their caliber. A heavy recoiling .458 isn't
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likely to produce as tight a group as a conventional .224 short case
|
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benchrest cartridge using specially selected primers, but if you
|
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compare similar kinds of guns and loads, you will soon see that your
|
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own home-built bullets stack up in the same way as benchrest .224
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bullets stack up against the average factory offering.
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You have nothing to fear in the accuracy department, in regard to
|
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the dies or the bullets you can make, given the material and care
|
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necessary. Do not, however, make the error of assuming that a perfect
|
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bullet will turn an average rifle into a benchrest gun. It will not.
|
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The errors caused by poor bedding, a light barrel, gas cutting in the
|
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throat or leade, improper powder charges, or even a less than steady
|
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shooter, will completely overwhelm the slight errors produced by a
|
|
bullet of average quality. No difference between a perfect bullet and
|
|
an average one could be told with most of the guns that are capable of
|
|
being carried afield, if the load is right and the shooter does his
|
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part.
|
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A good discussion of accuracy and bullet design can be found the
|
|
the textbook, "Rediscover Swaging". The techniques for obtaining
|
|
greater than usual core weight consistency and proper core seating
|
|
are also discussed in this book. Multiple passes at core swaging,
|
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holding the pressure for a consistent length of time, application of a
|
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precision film of lube rather than the usual transfer of lube with the
|
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fingers, and other factors that increase the consistency of results are
|
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discussed.
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