First thing I would do it clean and lube it.
Then get some factory ammo, Fed, Win, etc.
Get a quality GI mag, Pmag, Lancer, etc.
Then try it.
As a poster above said, Bushmaster has a rep for out of spec stuff. Chambers, barrels, canted FSB's, etc. A crappy Bushmaster 12 years ago, is what prompted me to start building my own AR's.
Then get some factory ammo, Fed, Win, etc.
Get a quality GI mag, Pmag, Lancer, etc.
Then try it.
As a poster above said, Bushmaster has a rep for out of spec stuff. Chambers, barrels, canted FSB's, etc. A crappy Bushmaster 12 years ago, is what prompted me to start building my own AR's.