so now we know the rest of the story ... since the barrel seems to be the problem, maybe another barrel swap would help get this one in line with the others?True.
It was missing the barrel, magazine and grips when I picked it up, I just added a GI barrel I had in the parts box and some stag grips along with a CM mag. Ran a few mags of hardball through it to check function and it went into the safe.