I'm not sure the exact serial, since it is locked up right now and I do not want to go get it. But I have put well over 2k rds through it of all sorts and never had ONE hiccup. Its fed and shot everything from 5.56 WWB to Brown Bear .223 to Remington UMC .223 and I have had zero problems. I really do not know what the problems ppl are having with the Golanis on the forums; they are always bitching about how shitty they are. MY father has one as well and his is in the same boat as mine, not a single problem.