I've only shot/owned one bushmaster. Its a Varminter. First shot it broke. It was a minor thing, but it broke nonetheless. It was likely broken before the first shot, but not noticed until then.
The roll pin that retains the forward assist sheared clean off. It then dropped a piece of metal inside the action.
Take it home, swap in a new pin in approximately 14 seconds, and its been fine since. I don't exactly run it hard though.
The trigger still sucked for a "match grade" though. ;)