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From: boyd@mailer.cc.fsu.edu (Mickey Boyd)
Newsgroups: rec.guns
Subject: Re: Walther PPK/S 380 ACP
Message-ID: <35138@mimsy.umd.edu>
Date: 2 Jun 91 16:17:28 GMT
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In article <35127@mimsy.umd.edu>, snitor!petert@uunet.UU.NET (Peter Toth) writes:
#In article <35058@mimsy.umd.edu> cash@convex.com (Peter Cash) writes:
##In article <35033@mimsy.umd.edu> boyd@mailer.cc.fsu.edu (Mickey Boyd) writes:
###In article <34989@mimsy.umd.edu>, gordonh@milton.u.washington.edu (Gordon Hayes) writes:
####Is there a full 9mm Walther PPK?
##
###No.  The direct blow-back action of the PP's would be rather painful in 
###9mm, and would also be very hard on the gun itself.  Walther does make a  
#
#Actually there is a 3in barreled  straight blowback .45 on the US market :^).
#You see, straight blowback actions are smaller than recoil ones.
#That's smaller, friend, not more shootable. Smaller.

The two types of automatic actions (for the purposes of this post) being 
compared are "full blowback" and "delayed blowback".  A full 
blowback weapon (for example, the HK P7 or Walther PPK) has a fixed barrel.
When a round is fired, recoil is absorbed by the weight of the slide and  
the resistance of the slide-return spring.  The full force of the round at the
time of firing must be absorbed by these two things (what is left over is 
what you feel).  Now, a delayed blowback weapon takes advantage of the 
ballistic fact that if keep the gun "locked up" for just a split second 
after firing the amount of energy imparted to the slide drops considerably.
Thus, in these guns (for example, a Colt 1911A1) the barrel moves WITH the 
slide for a small distance, which allows pressures to drop significantly.
The barrel and slide then part ways, and the rest of the sequence is as above.
I believe John Browning invented this type of action.  One advantage with this
type of action is that you can have a lighter (and thus SMALLER) slide on the 
gun.  

At this time I will pull a quote:  "In order for a pistol of reasonable
weight and dimensions to handle cartridges more potent than the .380 ACP, it 
becomes necessary to keep the breech mechanism locked up for a brief interval
after firing.  The usual term for that approach is delayed blowback."  (Dean 
A. Grennell, _Autoloading Pistols_, pg. 37).  

NOTE:  These are both "recoil ones".

NOTE:  You could also solve this problem with a REALLY strong slide-return 
spring, but then you would need some sort of big lever to chamber the first
round.  You would not be able to cycle the action by hand. 

So what is the name of the .45ACP?
-- 
             Mickey R. Boyd          |  "God is a comedian playing to an 
          FSU Computer Science       |      audience too afraid to laugh."
        Technical Support Group      |
      email:  boyd@fsucs.cs.fsu.edu  |                  - Voltaire