It is an A2 HBAR upper with a colt barrel stamped 5/95 and C MP 5.56 NATO 1/7 HBAR. The chamber looks chromed, but I don't know about the barrel? The muzzle has a 3 slot compensator that looks pinned in place. Here's a pic:
Brake pic Is the barrel threaded under the brake? The brake slots are at 9, 12, and 3 o'clock with a closed bottom. Is this comp loud? Can I drill (carefully) to remove the pin then unscrew it? What do I need to use to hold the barrel while removing the brake then installing a flash suppressor?
The upper has 0.25 inch diameter holes in both mounting lugs. The only mark is a broken A by the rear sight. I'm guessing this is not a colt upper. Here's a pic:
upper pic The bolt group and charging handle shows little wear and are unmarked. The bolt compartment in the carrier looks chromed. Here a pic:
bolt group pic