extractor issues. bolt lugs. doctored on single stage "GI" triggers( NEVER do this)go double/or worse. Thats about all I can recall, but the competition group we shot in for years didn't abuse their guns quite as much as others can/do. And a good chance most of them didn't start with the bottom line guns.
Other thing I"ve seen now, twice, since I saw it this past weekend, pin hole in a hammer not drilled straight which can cause issues.
