I received on trade an upper today that is suppsed to be a Bushmaster. It is a post ban style HBAR, unmarked barrel that is floated with a DCM syle sleeve and A2 handguards with no liners. The foundry code on the A2 receiver is "FS". It sports the match front sight (with set screw and small post) that appears to be soldered on (I don't see pins or set screws holding the FSB in place). The rear sight is a match sight that uses the screw in apertures in both positions.
NIce looking barrel. Appears to be a chrome moly barrel but there are no markings to ID it (twist, make, etc). You help is appreciated.