Was at the range yesterday, 103 degrees, but under cover. Noticed the fellow next to me had a stuck cartridge case in the chamber of his Smith and Wesson A4, could not get it out, he summoned the range master to help him, still could not clear it. I had heard years ago that if you pull on the rear bolt handle backward while bumping the butt of the stock downward on a bench vertically it will clear it, we did that, cleared the chamber. He was using Wolf steel cased ammo.
Got the gun apart to check for problems, totally bone dry, fairly new rifle. The owner said he had the local gun shop service it where he bought it, I was shocked that it could be totally bone dry, the range master was wondering how it could leave the factory without lubrication. So, we are not sure who is at fault, but if it left the gun shop's gunsmith like that, he should be talked to!
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I took the rifle and bolt assembly all the way down, and cleaned and oiled/greased it for the guy, I also had my Smith and Wesson AR-15 M & P at the range. I keep my A-4 heavily oiled and greased, 100% reliable. The fellow and his son then fired the rifle, works fine. It does answer a question of what would happen if you wanted to shoot an M & P bone dry. The fellow with the dry gun did manage to get it to shoot for awhile before the stuck cartridge case. I guess the AR-15 can work to some extent without lubrication of any kind!