Check the bolt buffer and slide extension assembly buffer. The latter are pretty easy to find and reasonably priced. The former not so much. Look up a guy who goes by WagonWheel on duckhuntingchat and have him make you a few. You need to disassemble (which is kind of a pain) to see the bolt buffer.
Do not shoot the gun if either of these is missing or cracked. If the slide extension buffer is missing, make sure the slide extension slides EASILY on and off the gun, and that the two prongs slide effortlessly into the matching holes on the receiver. The part bends easily when the buffer is missing (I had that happen) and that is the failure mode. In fact, check it anyway. The slide extension assembly is getting hard to find.
Other than that the gun is tank.
