From: towle%vssteg.dnet.dec.com@nntpd.lkg.dec.com (Clark Towle Gunsmith)
Subject: Re: Where do shot-out barrels go?
Organization: Digital Equpiment Corp. Salem, NH, USA

In article <CMI7B8.BJ5@fc.hp.com>, bartb@hpfcla.fc.hp.com (Bart Bobbitt) writes:

#Clark Towle Gunsmith (towle%vssteg.dnet.dec.com@nntpd.lkg.dec.com) wrote
#about worn out barrels:
#
#: I've also whacked off a few chambers
#: from barrels with shot out bores and
#: turned them into "mo gauges" for measuring
#: case stretch.
#
#Is this case stretch measuring done after the case is fired and before
#resizing?  Or done only after sizing the case?


 Mostly after the round is fired. It indicates the amount of case stretch both
longitidually and circumferencially which is an important consideration for
some people.

#: Some match shooters
#: and serious handloaders like to use these
#: devices to keep track of pressure signs.
#: signs.
#
#Could you please explain how a cut off chamber from a worn out barrel
#can be used to keep track of pressure signs?  This sounds interesting; I've
#not heard of this being done.  I don't understand how this would work.

 Basically it's a "home made" copy of the commercially available Mo Gauge.

 I set back and rechamber the worn out barrel chamber with the same reamer
that I use to chamber the new barrel with, then make a threaded cap for the
end that has the receiver threads on it. The threaded cap has graduation lines
on it that indicate the amount of case stretch in thousandths of an inch.

 Cases in a M1A typically grow about .005" so if you are working up a new load
and you test fire a few rounds where the cases are growing more than .005" you
can pretty safely say these rounds are hotter, or higher pressure.

 The threaded caps indicated reading on an unfired cartridge equals the
minimum chamber headspace dimension of the rifles chamber. After the round is
fired, it is measured again and this number indicates the amount of length the
case has "stretched" and some people use this "stretch" as a gauge to indicate
pressure. Also, if the fired case has expanded circumferentially and will not
easily enter the gauge, you can assume it is a higher pressure round as well.

 The same gauge can also be used as a loaded ammo Go, No-go gauge to ensure
all the loaded rounds will chamber ok.

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