From: hes@ncsu.edu (Henry E. Schaffer)
Newsgroups: rec.guns
Subject: Case Life Experiment
Date: 10 Nov 92 03:16:46 GMT
Organization: North Carolina State University


  This is a progress report on my .38 Special case life experiment.  
It might even be a final report.  I'm not sure if I will continue
it any further.

  I was curious about how many times I could reload these cases, so a 
couple of years ago I took 100 Winchester .38 Spl cases, and started 
loading them.  I used a CCI small pistol primer, 3.7 - 3.8 gr. Bullseye 
and a 158 gr. lead round nose hard cast bullet, with a medium roll crimp.
The motivation was plain curiousity about case life with just a bit
of wondering about the economics of reloading.  After all, the case
is the single most expensive component.

  This is a medium hot load for a plain .38 Spl - the Hercules powder 
booklet gives 3.6 gr. as the suggested load, and the Lyman reloading 
handbook gives 4.2 gr as the maximum load.  My load chronographs at
an average MV (actually measured at 15 feet from the muzzle) of
816 fps (avg of 10 shots, SD 18) which faster than the "usual"
755 fps (while +P is considered about 890) - all out of 4" barrels.

  In between I clean them in a Lyman 600 vibrating cleaner.  Then I
decap/resize with a carbide resizing die, and then clean the primer 
pocket with the little Lee handheld tool.  I've never had to trim, but I 
did have to enlarge the primer pockets once with a primer pocket 
reaming/truing cutter since it was getting too hard to seat the primers.  
I haven't done anything else, and particularly haven't annealed the 
case mouths.

[Various portions below were written at different stages of the experiment.]

  I've just finished cleaning and inspecting them after firing them for 
the 20th time.  94 of them look to be in very good condition, with just 
an occasional bit of tarnish near the case mouth (which I don't worry 
about, because it could be removed by leaving them in the cleaner for
an extra hour or a bit of rubbing with a Krazy Kloth.)  I found the
first cracked case mouth after the 17th firing, it was a crack running
down from the mouth about .03"  long and it went through the metal
to the inside.  I then also found 3 more cases with much shorter cracks
which didn't go all the way through the metal.  This inspection was
done by rubbing a fingernail along the crimp area and looking with
a headband magnifier (about 2X.)  The rim area which has been 
alternately flared, crimped, shot and resized has gotten a bit thinner,
for perhaps the end 1/50".  It probably is this working of the metal
which has produced the cracks I've found. 

  I kept on reloading all of them and shooting them.  Even the ones
with the cracks.  My reasoning was that that portion of the case isn't 
exposed to pressure until just before the bullet leaves the mouth, and 
at that point the lower case wall has already expanded to the cylinder 
wall so as to provide a seal, and so there is essentially no danger.  
Also I took care to shoot those rounds with extra eye protection.  My 
reasoning is probably "reasonable" because the cracks have been 
propagating very slowly since then.

  After 20 firings, I now have two cases with cracks about .04" long,
and 4 more with cracks about .02" long.  All of the cracks go all the
way through the case wall.  A knowledgeable friend feels that the
most immediate bad result of continuing to use these would be that
the worst cracked cases would not hold the bullet tightly.

  So I've found that case life (for this load) can be *very* long.
The economics lesson is also interesting.  At this point, the case cost 
per reloading is well below the cost of the primer, and so has faded into 
insignificance.  I'm wondering now if it is worth continuing this
experiment any further.

  Well - as a result of some encouraging letters and my own curiousity
I decided that I might as well keep on with this experiment - so I 
removed the 6 cracked cases, plus one more good case which I managed
to carelessly crunch when decapping, and I'm continuing with the
remaining 93 cases.  I took the good/crunched case and cut it 
lengthwise (from mouth to base) with a jeweler's saw so that I could
examine a cross section of the case wall.  (Actually, I just cut down
as far as the groove above the rim and then cut across the base at
that point.)

  The wall was in perfect condition, smoothly, gradually thinning 
down from near the base to about halfway up and then thinning barely
after that - with no stretches or other suspicious looking features.

  I'm now getting ready for the 25th loading of these cases.  I 
cleaned them more thoroughly than usual so I could carefully check
them (actually I forgot to shut off the cleaner and let it run all
night :-).  I looked them over and ran my finger nail around the
outside rim of all of them, and checked any suspicious ones with a
magnifying glass.  I found 6 with very small cracks - none longer
than the length of case which is crimped over - so I'm going to
reload all 93 again, but keep track of these 6.

  These 93 have now been reloaded 27 times.  The marking pen marks
have been polished off the cases by the cleaning process, but there
clearly are no large cracks yet.

  I've just fired these 93 for the 30th time.  Then I cleaned them more
thoroughly than usual and did the same type of finger nail and
magnifying glass check of the mouths of all of them.  I found 16 cases
with any kind of detectable crack.

  6 were very small (1/32" or less) just in the part of the mouth
  which gets bent in flaring and crimping.

  8 were somewhat larger (over 1/32", but never over 1/16"), and
  some went just below the part of the mouth which gets bent.  6
  of these looked somewhat serious, with crack propagation visible
  at the base of the crack - with the crack looking a bit like an
  upside down T or Y.

  2 had incipient cracks in the side near the mouth, but not going
  all the way through the wall and not quite reaching the end of
  the mouth.  One case had two cracks each about 3/32" long and on
  had two cracks each about 1/16" long.

  I wouldn't be worried about loading and firing any of these, 
although I suspect the 6 with the larger and more serious cracks
would get worse in just a few more reloadings.  Even eliminating
all 16 cases leaves me with 77 cases in fine shape out of the
original 100.

  I've answered my original question, and have seen that the life
of cases is really very long even under the unfavorable conditions
I chose (medium hot load, and medium roll crimp.)  The roll crimp 
appears to be the biggest factor in the cracking, and I suspect
that the case length would be even longer with a taper crimp.  (I've
bought a taper crimp die, but haven't started using it - partly
because I shudder that the thought of another experiment this
big, and partly because it would require another pass through the
press when reloading - yes, this has all been done on my single
station press.)

  The conclusion for the economics issue is clear.  After 30 
reloadings (or 20) the average cost of a piece of brass per
reloading is considerably lower than a primer and has essentially
faded into insignificance by becoming the lowest cost component
in the process.

--henry schaffer  n c state univ