From: rdh@sli.com (Robert D. Houk)
Subject: Re: Black Market guns
	<1992Sep12.193719.8488@ucsu.Colorado.EDU>
	<1992Sep15.221146.3029@gtephx.UUCP>
Reply-To: rdh@sli.com (or uunet!sli!rdh)
Organization: Software Leverage, Inc. Arlington, Ma
Distribution: usa
Date: Sun, 27 Sep 1992 16:39:13 GMT

   > >>>One of the functions of the "thin" cartridge case is to seal the firing
   ...
   > >>Not in a revolver (where the chamber isn't sealed normally) or, I think,
   > >>a bolt action rifle (where the bolt should go a long way towards sealing
   ...
   > I'm fairly sure, however, a revolver would be fairly safe to fire
   > in the way mentioned: Hot gas _already_ leakes out of the chamber, and
   ...
   Hold up!  Smaller ("pop gun") pistols may do fine.  However, I know for
   a fact that a .357 magnum revolver does rely on expansion of the case

I don't know a) what started this thread (missed it); or b) what it's
doing in talk.politics.guns/alt.society.civil-disob, but...

*ALL* modern center-fire (and rim-fire too) firearms (well, maybe "*ALL*"
is too encompassing, but certainly "virtually all", including .38/.357/9mm/
etc handguns, .223/.308/etc rifles, etc, and so forth) do in fact rely on
the "brass" cartridge case expanding and sealing the firing chamber in or-
der to ensure the burning/expanding gases force the other seal ("bullet")
out the only other opening left ("barrel"). In a bolt-action (lever, etc)
rifle (or pistol) the bolt/breech serves only to hold the rear-chamber-
seal ("cartridge case") in place; it has to withstand no pressure -- just
a hellofalot of force. (Typically, however, thought is given to channeling
untoward "pressure" (cartridge case ruptures) in some more-or-less harm-
less direction -- e.g., channels/cutouts to "vent" hot (*HOT*) gases away
from the shooters eyeball!) In a revolver, the cartridge case does move
backwards under recoil force until it is abuted against the rear surface,
at which point it stops, finishes sealing the firing chamber, and forces
the bullet down the barrel. Yes, significant gases escapes from the cy-
linder/barrel gap (industry standard typically .005-.007 inches). This
gas is under tremendous pressure (for most "magnum" loads like .357/.44)
around 35,000PSI (and very *HOT* PSIs at that), and will "erode a [very
nasty] channel" in any human flesh nearby. This is why IHMSA shooters
wear very heavy/fireproof/etc leg shields for shooting Creedmore position.
If the brass is subjected to sufficient pressure, it will mold itself to
the breech surface. Very accurately. Jamming the revolver. Add some more
pressure, and the thick/strong web (back end of the cartridge) will likely
rupture. Notice that there is lots of exposed human flesh (fingers, thumbs,
etc.) near the back end of the cylinder, and none near the front . . . 

Now maybe a finger held next to a .22LR revolver cylinder gap when fired
may yield nothing more serious than a !YEE-OUCH! (and other more trenchant
four-letter Anglo-Saxonisms), a nice burn/blister, and a dropped pistol,
but any more-powerful pistol (say, .357 Magnum) will cause serious damage,
yielding much blood.

This "sealing" action is why the aluminum-case "Blazer" ammunition by CCI
is not reloadable - aluminum does not "recover" like brass, it stretches
and seals once, and is permanently deformed.

					-RDH