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

a typical rifle-style bullet, or a smooth rounded or angled bullet nose of
any type, not having a lead tip from where the jacket stops to the end of
the bullet.
The semi-blind hole die is used whenever the nose or base of the
bullet has to turn inward, away from full bore diameter, without a shoulder
or step. Conventional rifle bullets, boattail bullets, and modern jacketed
handgun bullets with the jacket curving or angling smoothly inward
from the shank to the ogive all require the use of this die design.
By “semi-blind hole”, I mean that the hole in the die is not straight
through the die, but is shaped like the bullet itself. At the tip is a very
small punch to push the bullet out by its nose, and this punch is retracted
a short way up into its little access hole so there is no possibility of the
bullet material pressing against it (which might otherwise bend the small
diameter punch under those tons of pressure).
The “Point Forming” die, which we abbreviate “PF”, accepts either a
lead core, or the seated lead core and jacket combination swaged in the
core seat die. A full-diameter external punch shoves the material into the
point forming die. The material is compressed inward in the small end of
the die, giving the bullet its smooth curve or angled nose (the ogive). The
pressure also expands the shank slightly to final diameter.
The bullet material follows the die wall, right up to the ejection pin
hole and into it, if you push too far. This would put a little parallel “pipe”
on the tip of the bullet, which means you need to back off the depth
adjustment (the punch holder) just a little. The smallest tip which you
can put on the bullet using the PF die is the diameter of the ejection pin.
The smallest ejection pin that can be used is one that will withstand the
ejection pressure without bending. If you happen to forget to apply swaging
lubricant, or if the jacket is larger than the die cavity diameter, the pressure
required to eject the bullet can go considerably higher than the design
parameters. This means that the ejection pin needs a little extra diameter
as a safety margin.
A typical ejection pin (the internal punch for a point forming die is
usually called an ejection pin) for .224 or .243 caliber might be in the .062
to .081 inch diameter range, depending on the expected ejection pressures
and the abuse expected for the die. Dies made for professional bullet
makers, who know how to stop short of bending the punch if anything
goes wrong and who won’t be upset if they do need to replace the ejection
pin now and then, might tend to be closer to .062 inch; dies made for
experimenters who will be exceeding the design limits frequently tend to
have larger ejection pins, as do dies made especially for lead tip bullets.
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