Those handguards are fake. I would think it had rail covers on it, but the line through the middle says A2 handguards, but the piccatiny rails on the top and bottom say A3/A4. It is possible to mount the rails on an A2 handguard, but those in the pic are built-in. Also, the PEQ-4 looks like it's glued on because there are no rails on the side.
But what I meant was:
-Used my Marines, current USMC rifleman standard-issue is the M16A4
-Three shot burst, so either A2 or A4
-Non-detatchable carry handle, so has to be A2
-4x32 optic, US Military uses the Trijicon TA31
-M16 has a 20" barrel, the TA31A4 was designed for 5.56 NATO fired down a 20". The TA31M4 is for the M4's 14.5" barrel. There is a very slight difference in bullet drop
-I really like the M16, so subconsciously I must've assumed that's what the BR55 was based on.