From: toby@stein.u.washington.edu (Toby Bradshaw)
Subject: Re: holy smokes! bulged 9mm brass, overloaded?
Organization: University of Washington, Seattle

In article <232bog$sdo@news.u.washington.edu> toby@stein.u.washington.edu
(Toby Bradshaw) writes:

#In article <00970172.1E0124C0.15284@dymaxion.ns.ca> rr@dymaxion.ns.ca
#(Rod Regier) writes:
#
##By the way, each time "rimless" brass is subjected to normal
##firing pressures, the rim gets a little wider.
##After several firings, the headstamp gets fainter and
##fainter, and the rim gets wider and wider.
##That's one of my other hints that some brass
##is coming due for retirement.
#
#I don't think so.  In competitive benchrest, where pressures are a mite
#higher than any semiauto handgun, cases are re-used 100-150 times.  They
#don't get any bigger with use, and the headstamp doesn't get fainter.
#As long as the elastic limit of the material is not exceeded, the
#working lifetime is very, very great.
#
#-Toby Bradshaw
#toby@u.washington.edu
#
#
#[MODERATOR:  Hmmm, just FWIW, two additional data points:  First, one
#of my local shooting buddies has some .45 ACP brass he has handloaded
#since (we joke) John Moses Browning was a youth out hunting frogs with
#a slingshot.  He has complained to me that some of the brass has begun
#to flatten out, such that the head is slightly wider; he noticed this
#when some of the brass was repeatably failing to feed, and not slipping
#up into battery. A check with a mic reveals that indeed these are more
#than just a few thousanths over spec diameter.  I found this when some
#of our brass got mixed up during a match, and, indeed, on a hunch I got
#out the mic after *I* subsequently experienced some failures to feed in
#reloads.  Sure 'nuff, too wide, flattened out.  I pitched them (and use
#this as excuse to rag my buddy, when he seems like he needs ragging ...)
#Second data point:  some rimless rifle brass can indeed be reused many
#times.  But some cannot.

Must be awfully soft brass.

#Consider, for example, .308win cases, where
#you will get perhaps a few handloads before the risk of head separation
#becomes too great (Henry S. and I spent some time sectioning a lot of
#brass which I was using in my gas gun; the number of loads before we
#saw definite signs of stretching depended primarily upon how much I set
#back the shoulder, and also how much over spec was the chamber headspace
#in the rifle firing it.)  This phenomenon is reported in many of the
#handloading books; so we should perhaps have care about making blanket
#statements such as given earlier.]

If you move the shoulder, or use an action that stretches enough
on firing to let the case grow, you will get head separation sooner
or later.  I've reloaded .308 cases more than 20 times with no
sign of impending head separation, but I don't move the shoulder
back.  In a quality action with a solid lockup, and brass of
decent quality and strength for the working pressures of the
cartridge, and a chamber cut by a reamer of reasonable fit to
the brass, the life of the brass is way over a hundred rounds.
Anything less is due to design or materials flaws that limit the
working life of the brass.  Sometimes one may care more about
rapid fire than brass life; fine.  If I had brass that was deforming
inelastically under normal firing pressures, I would junk it.

-Toby Bradshaw
toby@u.washington.edu

From: toby@stein.u.washington.edu (Toby Bradshaw)
Subject: Re: Questions of reloading, and economics...
Organization: University of Washington, Seattle

In article <1993Aug23.221036.21188@ke4zv.uucp>,
Gary Coffman <gary%ke4zv.uucp@mathcs.emory.edu> wrote:
#Rifle casings don't last as long either. When loaded to near
#maximum pressures, you'll be lucky to get 10 loadings out of
#a piece of brass.

Not so.  Typical benchrest brass operating at above what are
considered normal maximum pressures for hunting ammunition are
reloaded 100-150 times.  The key to long brass life is to work
the brass a minimum amount.  If the cases are FL sized every
time and headspace becomes larger than zero, you can expect
case head separations sooner rather than later.  If you drag
the case necks over a rough expander ball after being squeezed
far below SAAMI minimums in your die, you can expect split necks.
Use of Wilson-type neck dies will have rifle brass lasting way,
way over 50 reloads at maximum pressures even in a sloppy factory
chamber.

-Toby Bradshaw
toby@u.washington.edu