My Tippmann M4-22 chomps rounds
I haven't shot this gun too much yet -- maybe 1200 rounds. It's nonetheless been good practice for dealing with malfunctions. It randomly crushes a round between the chamber and bolt, and it's frequent enough to be quite annoying.
This is what happens: https://i.imgur.com/mpwfOR4.png
I should've gotten a picture of a crushed round in situ while at the range, but I'm a dumbass, unfortunately, so enjoy my crappy recreation. It's more violent than shown; I didn't really draw it right. The case is getting bent! As the bolt rebounds forward, it grabs a round from the magazine but fails to put it into the chamber, instead squishing and bending the hell out of it.
I had a minor stockpile of Federal AutoMatch and 38-grain Aguila something-or-other. I'm mostly sure it does it with both types, but I'm too dumb to pay proper attention and make notes while I'm there. I should know how frequent it was with each ammo type and which magazines of the three it was doing this on (if not all of them), but I don't. 🙄
After an earlier trip where the gun was doing this, I field-stripped, cleaned, and oiled it. 22LR ain't a clean cartridge, so that should fix it, right? I guess not: it happened within the first 5-10 rounds this range trip. To me that points to cleaning and oiling not being the problem, but what do I know?
Is there a proper way to diagnose it? Is the buffer in need of a stronger spring? Is it instead cycling too quickly and causing things not to line up as the bolt comes home? Could the magazine springs be weak? Do 22LR magazines need disassembly and cleaning to stay functional?