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Airgun Pellet Swaging

3/4-E ogive dual-diameter pellet

Corbin makes pellet swage dies for conventional .177 and .22 airguns as well as the full spectrum of diameters for specialty and precharged high-power airguns, including 45 and 9mm rifles, .12, .14, 5mm (20 cal) and .25 caliber. Any caliber of airgun projectile can be made using Corbin equipment.

The most successful high precision and high power airgun pellets can be swaged in two variations, one with the hollow base semi-wadcutter style and the other adding a dual-diameter flared base, so that the main body is reduced to ride on top of the rifling while only the edge of the skirt engages rifling and obturates the bore, reducing friction but allowing maximum alignment.

Keith nose single diameter pellet

A single-diameter pellet can be swaged in a single LSWC-1-S die. This die fits into the ram of the CSP-1 press. It forms the hollow base with an internal punch that also ejects the bullet from the die on the down stroke, and the nose is formed in a cavity in the end of the external punch. The edge of the punch forms a small shoulder, which gives this kind of bullet the general classification of "semi-wadcutter", regardless of the actual shape of the nose projecting beyond this shoulder. This kind of pellet has proven itself in international competition at the highest levels, provided the diameter is matched correctly to the chamber and the skirts are the proper thickness for the air pressure at the muzzle. (Too thick and there is poor expansion, too thin and the pellet base flares on exit from the muzzle, or separates in extreme cases.)

If you are interested in a complete package to make any caliber of straight-sided, hollow-base pellet, here it is:
  1. CSP-1 S-Press, also for reloading your centerfire cartridges.

  2. LSWC-1-S Lead SWC die, with HB punch, TC nose: specify diameter.

  3. CSL-2 Swage Lube, a little goes a long way.

  4. LW-10 lead wire, closest diameter that is smaller than caliber.

  5. PCS-1 Core Cutter, with die insert to fit above wire.

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Pro-1-R Pro-Swage Die To make pellets in a reloading press, here is another complete package:
  1. PRO-1-R with hollow base, Keith nose.

  2. CSL-2 Swage Lube, a little goes a long way.

  3. LW-10 lead wire, closest diameter that is smaller than caliber.

  4. PCS-1 Core Cutter, with die insert to fit above wire.

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To determine the proper diameter, fire a few pellets into a soft media that will catch them without damage, such as water or oiled sawdust, and measure the bore diameter (smallest diameter between rifling). The pellet should be swaged so it slips into the chamber easily but very closely.

The skirt of the pellet needs to be thin enough to expand quickly into the rifling of the barrel, yet not so thin it will flare when it exits from the muzzle. This is controlled by the diameter of the conical probe machined on the end of the hollow base punch. It is fairly simply to make the skirt thicker by turning a small amount off the diameter of the base punch's conical extension with a ceramic tool bit (high speed steel bits will be damaged by the tough punch material), so if in doubt, a thinner skirt is good as a starting point. Standard thickness is usually 0.015 inches.

Typically, a .22 Airgun will use a pellet that is about .218 diameter, but this can vary with the make and model, the age, and other parameters. You can determine the diameter of pellet that works best in your gun, either by measuring it or by sending several samples, well protected against being smashed, to Corbin for measurement. Diablo-type pellets tend to vary in diameter because they are dented and made out of round in handling and bulk packaging, but a selection of several which fit into the chamber of your gun properly can give a good average reading.
pellets

A dual-diameter (bore-riding pellet with a rotating band to engage the rifling at the edge of the skirt) pellet can be swaged two ways:

  1. In two dies, the LSWC-1-S and the DDS-1-S.
  2. In a special DDS-1-SC that combines the functions of both of the above dies.
The main difference between the two methods is that the two-step, two-die system gives you a little more control over the over-all length and the length of the major diameter rotating band, whereas the single die system is faster and gives you almost as much control. The cost of the two-die system is slightly less than the more complex single custom die, but production speed is nearly doubled with the single die (one stroke per bullet instead of two).

The operation for a two-die system (LSWC-1 and DDS-1) is as follows:
  1. Cut or cast the cores from 1-3 grains heavier than desired in the pellet. Corbin's pure lead wire in 70,000 grain spools can be cut quickly with the PCS-1 core cutter.
  2. Using the LSWC-1 die, insert the core and adjust the top punch to give you the exact weight desired by extruding away 1-3 grains along with the variations. The press ram is first raised all the way, and then the top punch lowered and adjusted in small increments by turning the punch holder to achieve the desired weight.
  3. The pellets are now full or major diameter cylindrical shank design. To make them into bore riding style, install the DDS-1 die and punch, and push the bullet nose-first into the die. The nose punch in the DDS-1 die must be of the same shape as in the LSWC-1 die, to maintain the nose. This punch is of course smaller in diameter than the LSWC-1 nose punch, so the two are not interchangeable.
  4. Raise the ram all the way up and then adjust the punch holder, with the base punch installed, to push the pellet as far into the die as you desire to reduce the diameter. Do not run the base punch so far into the die that it completely reduces the shank, or the punch may strike the smaller diameter section of the die and be damaged. (Some systems have a collar on the punch that prevents this from happening, which we call the "crash proof" punch - but only when used with this specific die).

dual diam. pellet The best nose shapes discovered so far are either a Keith style (flat or truncated conical) or a small round nose. These give better BC without excessive forward weight, allowing higher velocity than a traditional rifle bullet shape with the airgun pressures. The best base cavity shape is one which reaches nearly to the middle of the nose form, using the mass of the lead core to form a shank length at least one caliber and preferably a caliber and a half long.

This style can be improved further with the addition of a DDS-1-S dual diameter sizer die. The pellet is formed as previously described, and then pushed into the DDS-1-M die and back out again, to reduce nearly all of its length by twice the rifling height (or groove depth). This means that most of the pellet will ride on top of the rifling, without being engraved. Only a small band is left unreduced at the rear of the pellet. The width of this band is up to the operator: more width is used for higher power (higher pressures) and less for higher velocity at low pressures. You can determine experimentally the minimum width that still prevents skidding and stripping across the rifling, and maintains a secure air-tight seal. If the skirt area is thin enough, and the pressure is high enough, the skirt will expand at the rear edge to cause a good seal even without the band. But having the band means that you don't have to rely on consistent air pressure for the seal, removing one possible cause of inaccuracy.
custom DDS+LSWC die The ultimate tool for speed and ease is the DDS-1-SC which combines the lead semi-wadcutter weight adjusting "bleed holes" feature with the dual diameter sizing, all in one stroke. To allow adjustable weight without excess skirt length, the internal punch can be adjusted for length of protrusion into the die. This is done with a self-locking nut on the threaded shaft of the punch, and a hex socket in the end of the punch so you can hold it with a hex wrench while turning the locking nut. The nut is adjusted toward the hex socket (away from the die) to shorten the nose section of the pellet, and toward the die (away from the hex socket end) to length the nose. Once the nose length has been set, the bullet weight can still be adjusted by the setting of the external punch relative to the top of the press stroke. Moving the punch holder down, closer to the ram, will make a lighter bullet by extruding away more lead (shorter skirt section). custom DDS+LSWC die

The custom die is the same cost as a LSWC-1 and a DDS-1 die pair, because of the additional cost of the adjustable internal punch, but the operation is twice as fast (meaning, double the production per hour). A new PUNCH-SA (or -HA) adjustable internal punch is required for different nose shapes. The same external punch is used for all weights and nose shapes. It is changed in order to modify the shape of the hollow base, or to make the skirt edges thinner (which would require a larger diameter conical shape on the punch, corresponding to a larger hollow cavity diameter at the bullet base). Thin skirts are used for low pressure guns, such as spring guns and most multi-shot CO2 cartridge guns, while thicker skirts are used for pre-charged high pressure guns.A very light film of Corbin Swage Lube, applied simply by having some on the finger tips and handling the lead cores (cut from lead wire or cast in a core mould), should be sufficient lubricant for easy swaging. A light coating of Corbin Dip Lube can be applied after swaging, to act as a thin film wax lubricant for the bore. Excessive lubricant in the nose forming punch may prevent the nose from forming completely. If this should occur, use a cotton swab to wipe out the nose cavity and use less lubricant.

Pellet made in the LSWC-1 die A pellet is different from a shotgun slug only in size, and in the fact that the low air pressure propelling it means some benefits will accure to the person who reduces bore friction as much as possible. Using the dual diameter design accomplishes this without the much higher cost and slower operation of making diablo type pellets. Actually, the same technique would work in a shotgun slug except that the slug does not usually obturate the bore, this task being handled by a wad column or a plastic cup, so the entire slug can be made small enough to fit in the shot cup instead of leaving the base at full bore diameter. The principles of flight and balance are the same, so the designs are very nearly the same except for diameter.

Q&A
Answers to commonly asked questions about swaging

Technical support and sales e-mail: send e-mailsales@swage.com

FAX: 541-826-8669 - call Corbin - PHONE: 541-826-5211

The phone is answered by real people from 9-AM to 5-PM, Monday through Thursday, and by a computer with hundreds of answers and voice information files any other time. None of us really like voice mail systems, but if you have a little patience, you can get a lot of answers in a short time by poking the buttons and listening to the responses. The alternative is to reach no one after hours, or for the company to raise its costs by hiring around the clock staff and training them to answer your questions, which would of course mean the cost of the tools would go up as a result. Since we've have pretty good results holding down prices for the past 30 years, maybe the voice mail after hours isn't such a bad option. You can also send e-mail or a fax message any time, or you can drop us a note:

CORBIN
PO Box 2659, White City, OR 97503 USA






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