Headspace is basically the amount of play a cartridge has in a chamber. There has to be some to account for manufacturing variations in guns and ammunition, but too much or too little can cause problems. Too little can cause extraction problems and poor accuracy. Too much can cause poor accuracy as well, and also shoulder separations, case head separations, and kabooms.
VIDEO HERE (12:16 minutes)
I was firing a ma duece from the top of an M113 when the barrel detent went weak. Stacked and blew three rounds in my face when the barrel spun out of lock. Thats why headspace is important. Medics spent three hours picking scrapmetal out of me, and I lost a few teeth when a piece went clean through my face. One piece came within 1/2 inch of my femoral.
ReplyDeleteI'm not anon, I'm Unclezip.
DeleteUnclezip:
DeleteAnd this has to do with what, exactly?
I believe he’s referring to headspace and timing settings on the Browning M2 .50 caliber machine gun, which had to be set manually every time the barrel was changed or the gun was disassembled/reassembled.
DeleteThanks, Chad. I suppose I should have embellished it more for the slow readers in the crowd. Elmo..you go now.
DeleteHad a brief hands-on course many years ago on installing the barrel and setting the headspace on the M2. It was stressed that paying attention and getting it right was very, very important to your health as an operator. Good example why right there.
DeleteI didn't put together you were the one who had posted the original comment.
DeleteThanks for the clarification.
Merry Christmas.
Yep. The head space on the ma deuce is variable, as it is set by how far into the receiver you screw the barrel when you put it together, like most rifles with threaded barrels. The difference is the barrel on the ma deuce is easy to take off, and required to be done when you clean it or transport it without a vehicle.
ReplyDeleteI assume that "the barrel detent went weak" means that the barrel unscrewed a little. I guess a cost of being designed for quick barrel changes in the middle of battle is that such screw-ups are possible. Many other quick-change designs have been found since 1933, but apparently the US Army doesn't consider any of them to be enough of an improvement to replace Browning's design.
ReplyDeleteBarrel changes are the only practical solution to the barrel overheating when the guns have to continue firing. They learned this was necessary in WWI battles such as Verdun, where French machine gunners shot down attacking Germans until the battlefield was blocked by piles of bodies, then needed to shoot some more when the German generals drove their men to climb over the piles. The Germans lost about 11,000 men a day for 302 days; somehow the French lost even more. And the front lines barely moved...