HB-9 updated text (PDF) - Corbin Bullet Swaging

center of gravity and create fast, light but long projectiles. In short, just
about anything that can be launched from a small arm, be it airgun, shotgun,
rifle or pistol, and some kinds of machine guns and cannons, can be
swaged and is considered a bullet.
Bullet swaging (SWAY-jing, sounds like “paging”) is the process of applying
extremely high pressures (from 15,000 PSI for soft, unjacketed
bullets to as high as 150,000 PSI for solid copper bullets) to materials
contained in a very tough, extremely well finished die, so that the material
will flow at room temperature and take on the shape of the die and the
ends of the punches.
A die is a vessel to hold the pressure. A punch is a rod that fits into the
hole in the die and seals off the end. If you refer to a punch as a die and
vice versa, you may cause some interesting errors when placing orders.
One of the first things to learn is the right names for the basic parts involved
in the swaging process. You wouldn’t call a pistol a shotgun, would
you? Probably not, or else you might get some odd-looking mail-order
holsters!
A business that is good at making swage dies probably will be buried
in orders, with long waiting lists. Waiting up to a year to get your “die”
and finding out everyone thought you wanted the “punch” that you asked
for may be frustrating. Use the right terms and avoid this problem.
In swaging bullets, you will always be putting a smaller diameter object
(lead, jacket, or a combination of both) into a slightly larger die cavity
or hole. Each step in swaging increases the diameter of the components,
until they reach the final diameter in the last die. Swaging never
reduces the diameter. You will only have stuck bullets and hard ejection if
you try to push a slightly larger part into a slightly smaller hole. This is
the difference between swaging and drawing. You never swage anything
“down”. You never draw anything “up”.
In drawing, you do push a larger part through a smaller hole, to reduce
the diameter. This kind of die is a ring, not a cylinder closed on one
end. The jacket or bullet that you are reducing is pushed through the ring,
and is decreased in diameter when it comes through the other side.
We use drawing to make longer, smaller caliber jackets from shorter,
larger diameter ones. Also, within some narrow limits, it is possible to
make a smaller caliber bullet from a larger one, although this degrades the
quality of the bullet unless special conditions are observed. Usually the
difference in diameters has to be within 0.006 thousandths of an inch
when you reduce finished bullets by drawing. Jackets can be drawn much
more than this, usually up to 30% smaller in one draw.
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