I load 5 rounds in my M1A and fire them as normal. Average velocity was about 2645 FPS and I saved the 5 cases. I then loaded another 5 rounds and turned the gas system off on the rifle. I fired those 5 rounds manually cycling the rifle for each round. I saved those 5 cases. My average velocity gained about 50 FPS so nothing exciting there. However, when I measured the 10 spent cases they all measured identical right down to 0.001", every case measured 1.635" so each case grew 0.005" whether the cases were manually cycles or semi-auto cycled they came out the same. Not what I expected and not in line with what you mentioned. Got any theory?
The remaining 10 rounds went through my bolt gun and went in at 1.630" and came out at 1.632" all here nor there but why were all the M1A cases the same with the gas on or off? Anyone?
I hope no more of this is posted because it will blow my theory all to heck. :banghead:
All my M1a's are match rifles with the gas system disabled. The gunsmith I use does it the old AMU method, drilling screws through the gas cylinder to hold the the upper ferrule to the gas cylinder. Personally, I recommend welding those two together. But, never disabled my gas system on either a M1a or a AR15.
Size those cases and try again. On the first firing, my cases all grew to max trim length, and around reload three to five, only required 0.001" or 0.002" trimming. Maybe something will show up once those cases are fired again in the same rifle.
By the way, I lubed my M1a cases and was able to shoot them 23 times without a single case head separation. Your dry cases, five to eight reloads is what shooters typically got before the case heads came off. You want to spend more money, run them dry, and use your cases up quick.
These are cases fired in my M1a and fired as lubricated rounds. I either left the RCBS case lube on them and primed them that way, or I put on Johnson paste wax on the loaded cases with my fingers. I don’t like the feel of greasy cases and if I had time between matches I would wash the cases to remove the RCBS lube and then apply paste wax. . If I did not have time I fired the cases just as they came out of the die, minus whatever lube that was lost in handling. I never had a primer dud. I ran a number of experiments with various lubes; leaving thick coatings of grease is objectionable as grease particles are in the air after firing. I had 1000 rounds of CAVIM and I fired most of them in a FAL. FAL’s are very hard on brass and I experimented with stick wax. This is a tenuous grease used to lubricate saw teeth. I dropped lumps of stick wax in a bag with handfuls of CAVIM and shook vigorously. Both case and bullets were unevenly coated with globs of stick wax. When I fired this stuff it was as if a grease bomb went off: the mechanism and myself became coated in stick wax. My shooting glasses had to be frequently cleaned, my hands were greasy, my clothes were greasy, overall, it was messy. Later I spent hours wiping the cases to reduce the amount of stick wax.
So, I prefer thin coatings and after all the handling that occurs after sizing, after trimming, after priming, after dumping the powder and seating the bullet, the amount of RCBS case lube left does not leave objectionable residue in the mechanism or eyeglasses.
At Camp Perry in cold weather I had bolt over rides with some of my Johnson paste waxed rounds. This ended when I polished the rounds. Previous to that I shot the rounds with swirls and gobs of paste wax but that caused sluggish round rise in the magazine in cold weather. From then on I polished my rapid fire rounds and have never had a bolt close on an empty chamber even in rapid fires sequences in snow.
I have tried various lubes, paste wax takes the most time to apply but is the most satisfactory for handling. Paste wax dries hard, it is easy to wipe off dirt if you drop a round, and it is cheap.
I tried wire pulling wax, bought a bottle at Home Depot, works but not as hard as paste wax.
http://www.shop3m.com/wire-pulling-lubricant-wax.html
Sometimes I left Kiwi Mink Oil on the cases.
The picture below are of sectioned cases, R stands for reloaded, R5 five times reloaded, etc, all of these cases the shoulder was set back about 0.003” and the cases fired in my M1a. I do not visually see any evidence of case wall thinning from those cases reloaded 5 times (6 times fired) , R18, or R22. As long as the case is not excessively stretched during firing or extraction, there is no reason for the sidewalls to thin.
The FAL cases are from a Bud’s rifle. I think they were separating after 2 or 3 three firings, FAL’s are hard on brass.
