This is a Bushmaster flattop upper with a flat top gas block with rails. Barrel is is 16" and marked BMP 556 NATO 1/9 H BAR. It is an AWB upper, as it has no bayo lug nor flash suppressor. Assembly is in good condition, but it does have a gouge in the handguard ring.
E-mail for pics.
Does not include B/BC/CH
$290 $260 plus $15 shipping to lower 48.