I have just under 2000 rounds through this gun. It jammed up on me the last time I took it out. I just disassembled it today to figure out what was going on and I found the problem. The left side lug that is part of the barrel trunnion, which the barrel screws into, had sheared off and logged itself between the bolt and the receiver. I really like this gun, and I know that they are going to have teething pains. Having a machinist background, and looking at the part, I understand that it is easier to cast a complex part like this. My contention is that it needs to be made of real steel and not a cheap alloy. I have contacted ATI and will update this as soon as I get some info from them.

I'd be willing to bet they will take care of you.  Could you post a pic or two of the part that failed?