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

There are two more steps to expand the core inside the jacket, blowing
the jacket out like the skin of a balloon, and then form the ogive on
the bullet to finish it. That is for flat base open tip bullets.
But if you wanted to make a lead .308 diameter bullet for a .30 Mauser
pistol, then we’d make almost the same kind of die but we’d make it with
a bore of .308 inches, and fit it with the right kind of nose and base punches.
So you see that even if the dies look similar and work in a similar way,
their purpose really makes them different dies. That’s why we need two
different names for them. It helps avoid a lot of unnecessary explanation
and errors.
Perhaps you might order a .308 LSWC die, maybe with an “Autoloader”
nose and a “Cup Base”. We would use the short-hand “AL” for
Auto-loader, a sort of rounded semi-wadcutter shape, and “CB” for Cup
Base, which is a shallow concave base form. To us, the term “semiwadcutter”
is a general description for a bullet style that can be made
using a punch to form the nose, instead of a point forming die. The Target
Wadcutter, Button-Nose Wadcutter, Keith, Auto-Loader, and even round
nose SWC styles are all subsets of the semi-wadcutter group, since every
one of these styles is made in the same die just by changing the nose
punch.
Two other kinds of dies that are made with a straight hole and two
full-diameter punches are the “Lead Tip” die and the “Core Seat” die.
These don’t have any bleed holes around their middle. The core seat die
is also called a “Core Seater” and abbreviated “CS”. The lead tip die is also
called a “Lead Tip Former” and is abbreviated “LT”. It is not the same
thing as a point former or “PF” die.
The purpose of a core seat die is to expand the jacket, which is made
slightly less than final diameter, and at the same time achieve a very tight
fit between the core and jacket. You can use either a punch that fits into
the jacket, to make open tip style bullets, or you can use a punch that fits
the die bore, and thus make large lead tips. The use of a CS die to make
lead bullets (after first swaging the lead core to exact weight in the CSW
die) is a perfectionist’s way to build lead wadcutter or semi-wadcutter
bullets: it can be more precise because you separate the pressure needed
to extrude surplus lead from the pressure required to form the edges of
the bullet nose and base.
In a LSWC die, the pressure stops building when the lead begins to
extrude through the bleed holes. Thus, some shapes of bullets with deep
nose cavities or hollow bases and sharp edges may not receive enough
pressure to fully take on the exact punch shape, if that pressure is higher
than the pressure which causes lead to spurt out the bleed holes. By first
15