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Burn through 30-06
dtknowles
Member Posts: 810 ✭✭✭✭
Have you seen this before? The head of three 30-06 cases are shown in the picture. All three plus some more have the same burned through length wise slots about an eighth of an inch long. I sectioned one, shown in the center, and there is no sign of incipient head separation. I can't say what the gun or load was as I found them on the ground at the range. Headstamp is REM-UMC 30-06. Sorry for the poor picture.
Tim
Tim
Comments
I would agree with the brittle brass diagnosis. Usually excess headspace will cause rings to appear parallel to the case head above the web or separate the case head from the body. Vertical cracks usually indicate a condition where the brass is weak or brittle and rather than expand the case cracks.
I would also add that if these cartridges are old enough that the brittleness may have been assisted by a fulminate of mercury primer. The mercury in these primers was metallic flowable mercury and after a certain period of time, it would migrate from the priming compound and amalgamate with the brass causing it to weaken around the head of the case.
The only reason I mention this is because the cases in the picture look old plus the REM-UMC headstamp could be from the old REM-UMC Company that was in business from about 1911 to 1934. Commercial primers from this time period were made with either pottasium chlorate or fulminate of mercury. The mercury primers were phased out by about 1945. While the mercury, contrary to popular belief, was not corrosive it would so badly weaken a brass cartridge case after one firing it could not be reloaded. If these were old, never reloaded cartridges someone had stored on their side for a long period of time, this may be the location where the mercury flowed and weakened the brass causing it to split with this pattern.
Regards,
Heavyiron
I had the exact same thing happen to me in my .257 Roberts. I had Federal Premium loads, 120 Noslers using +P brass. The flame cut on mine was about 1/2" though.
I contacted Federal and they said do not shoot any more of that batch. They sent me four new boxes for the two I sent in.
About three weeks later they said that after doing tests on the brass there had been a chemical spill on the bases and that weakened or hardened them to the point where they cracked and were cut through at that point. The brass had been made three years earlier.
If the brass that you saw looked relatively shiny on the outside this may have been the case with what happened there. If the brass looked dark in any way I would say reloaded too many times or too old. You didn't happen to see if the neck material was thin did you?
Emmett
However I've experienced extensive brass separations of new folded head 45lc brass in a new 2nd Gen SAA in the early '60s. I went round and round with Colt and Remington at the time sending several hundred fired and infired cases to them which they replaced with the then new solid head cased ammo. Colt's story was that they'd made that same oversize, tapered 45LC chamber to a couple of ten thousandths of an inch accuracy for some 80 years so the problem wasn't with them. Remington's new ammo didn't split.
I received a letter from Wagner at Colt a few years later stating they had revised their chamber dimensions downward.
The science of proper compounding, cold working and annealing of cartridge brass in the US really isnt that old.
I'm running about 30% split case bodies in Roumanian 7.62x25 ammo from 1953.