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|08-17-2008, 01:57 PM||#1|
Join Date: Mar 2008
Case Life, Case Stretch and Case Lube
Noticed and interesting thread on another board that mirrored my experience. Here is the post:
"Re: Case Life vs Case Stretch vs Case Lube
Posted By: slamfire
Date: Mon 11 Aug 2008 11:51 am
In Response To: Re: Case Life vs Case Stretch vs Case Lube (mojo-joe)
Back in 1999-2000 I tried to determine the useful longevity of lubricated cases in a stock 308 Winchester M1a Super Match. I fired the same cases 23 times in the same M1A without a case head separation. I started with approximately 100 once fired LC66 cases. These cases were all fired in the same rifle. They were fired in 58 round matches and 88 round matches. I kept records of the number of matches the cases were fired in. Since there would always be unfired cartridges at the end of a match, I tried to make sure that next match they were used first. Once the cases were on the ground it was impossible to segregate by exact reload number. So some cases were actually have been loaded more or less than others. All cases were full length sized in my Lee 308 sizing die, a Bonaza sizing die, or my RCBS small base die. The die choice depended on my mood, but the Lee die was used for the majority of reloads. I always removed the RCBS case lube after sizing and before priming. I relubricated the loaded cases by hand before shooting them in highpower matches. Most of the time the cases were coated with Johnson paste wax. Sometimes I used Lee Lube. I tried carnumba formula wax Rally paste car wax. The car wax was not as successful as the thicker film lubricants.
I lost many cases to the range gods. Primer pockets enlarged as the reloads increased. If the pocket did not tightly hold a primer I dumped the case. At the ninth reloading the primers appeared high in the pockets, so I reamed the pockets to a uniform depth. I reamed the pockets again at the 16th reload. There are a lot of scratches on the outside of the cases. I trim on a Gracey Trimmer which headspaces on the shoulder. For the first couple of reloads, cases needed to be trimmed almost 0.005-0.01". About the third or fourth reload the case growth decreased significantly. I ended up trimming only .001", if at all, between reloads, when used the Lee Sizing Die. Switching sizing dies has caused case growths to .005". On the next size and trim cycle, case growth is back to .001" or less.
Changing the sizing die seems to cause case length growth. If I change the sizing die, I end up trimming more material than if I had not changed dies. The first trim after resizing with a new die is usually in the .005" range. Then, if I size again with that new die, on the next reload, material removal is back to the .001" range. I do not know what is going on. I full length size the case to the minimum headspace(should be 1.630") as measured on a Wilson cartridge gauge. The rifle came with a tag that indicated the headspace was 1.633"
I sectioned cases that developed body seams. I never found any discernable internal evidence of a case ring or case necking. The case loses material each trim, but the location or amount of material loss is not visually detectable. The back one third of the case is dark and roughened, showing evidence of erosion. No case rings were ever felt using the bent paper clip technique on the good cases.
Accuracy is unaffected within the limits of my rifle and this shooter. I have fired overall HM scores at our club 100 yard reduced range with this brass, and I have shot HM individual scores during rapid fire at 200 and 300 yards, and occasionally at 500 and 600 yards. I am unconcerned/unconvinced that there is a measurable accuracy loss (or gain).
The last I fired this stuff was during the 2000 rattle battle at Perry. I picked up most of my cases but retired them."
Any of you guys had a similar experience?
|08-17-2008, 03:19 PM||#2|
Join Date: May 2003
Re: Case Life, Case Stretch and Case Lube
All I can say is WOW !! 23 reloads from the same case, the best I have done as a test was/is 9 and I had a few case head separations(LC Match and plain LC). They were trimmed every 3 firing the primer pocket gave up on a few before the 9th firing. After the 5th firing I scrap mine, my double lugged rifle has a H/S of 1.632 and my super stocker H/S is 1.633(nice for a GI barrel)
|08-17-2008, 06:11 PM||#3|
Join Date: Feb 2007
Location: South Carolina
Re: Case Life, Case Stretch and Case Lube
You might take a looksee at this post I did a while back which may help explain some of your experiences and why you are getting variables.
Also there is another one
These two cover alot on case life being affected by die dimensions and chamber dimensions which will help explain alot of things folks run in to.
Bottom line is FL dies are like women. No two are the same and some are much better suited to the job at hand than others.
what are the dimensions of your fired cases measured .200" up from rim? That tells the tale along with headspace.
23 reloads on a WW case is pretty good. On a LC case in a bolt gun I would be looking for 75 to 100 loadings minimum with a snug chamber and min headspace set up.
I have a 30.06 case that has been loaded 157 times and still has snug primer pocket and ready for many more reloads should I get time to get around to the testing.
Properly stress relieving the necks is also critical.
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