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From: snitor!petert@uunet.UU.NET (Peter Toth)
Newsgroups: rec.guns
Subject: Re: Reloading questions: 40 S&W and 45 ACP
Message-ID: <35559@mimsy.umd.edu>
Date: 13 Jun 91 02:00:03 GMT
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In article <35507@mimsy.umd.edu> boyd@mailer.cc.fsu.edu (Mickey Boyd) writes:
#In article <35456@mimsy.umd.edu>, n9020351@unicorn.cc.wwu.edu (James D. Del Vecchio) writes:
##
##Per mag maximum chamber pressure is about 35,700 cup for 38 super, 40 S&W,
##and 10mm Auto, vs about 19,900 max for 45 ACP.
##
##Why is this and what significance of it?  Are the 45 cases weaker for some
##reason, or is it the construction of the pistols?  Is it possible to make
##a 45 withstand the higher pressures?  Thicker cases maybe?
#
#The .45ACP is a low pressure round.  Way back in 190x, when the case was  

Was it 1906 that the German Namvy accepted the 9x19 (aka 9Luger, 9NATO) as their
sidearm round?  It too has a SAAMI max pressure of 35700.  Maybe age was not the
reason.  Maybe JMBrowning wanted light pistols.

#designed, the common case construction method was called "ballooning".  This 
#basically resulted in a case with less brass (but higher capacity) than cases
#currently made today.  Thus, cases made today are much stronger (in general) 

Apparently JMBrowning produced the prototype cases by hacking the .30-06
cases to .90 inch.  Since the 06 runs at circa 45000, it wasn't the case:
it was the thickness of the chamber, as Mickey points out below.

#than ones made 50 years ago or longer.  For the "older" calibers, this is 
#quite common.  Anyway, you can load a .45ACP "up" without harming the case,
#but you could harm the gun (because it was designed with a certain power 
#level in mind).  Also, if you stick one of these hotter loads in a really 
#old 1911, it might blow the gun up in your face!!  Thus, the moral of the 
#story is that extra case strength does not mean you can increase loads 
#willy-nilly.  Many variables exist in the "safe to shoot" equation, and 
#that is only one of them.  DO NOT LOAD ABOVE CARTRIDGE SPECS UNLESS YOU 
#REALLY KNOW WHAT YOU ARE DOING, AND QUESTION YOUR SANITY EVEN IF YOU DO. 
#[... rest of great article deleted ...]

Like Mickey said.

Peter Toth