Rolling the dice with this one.

Could not get a round to chamber with several different mags. The bolt lugs would jam trying to lock up and then would be impossible to pull out using the charge handle. Had to use a hammer on the charging handle to get the bolt unstuck. The extracted bullet case was beat to hell with dings and dents from one attempted feed. I sent it back and the 2nd was a little better but still jammed 80% of the time. I took sandpaper to the bolt interfacing surfaces and it helped a lot. I then dry cycled the bolt about 500 times and there was more improvement. I would say this has to be a machining problem either on the bolt or barrel extension.