The following weapons were used in the film Brothers:
In Afghanistan, Sam is threatened with a Makarov PM.
DOD police officers who confront Sam at his home pull what appear to be Glock pistols.
The M4A1 Carbine is seen carried by Marines who ride with Capt. Cahill in the humvee and by the Marines who engage the Taliban and recover Sam.
Norinco Type 56
The Taliban forces that capture Capt. Cahill are armed with Chinese Norinco Type 56 assault rifles. They can be identified by their full sight hoods, smooth dust covers, chromed bolt carriers, rivet pattern, slab-sided handguards and slanted front sight post. They cannot be early model milled receiver Russian AKs because they all have stamped receivers, although they share some design features, like muzzle nuts and ported gas tubes.
The semi-automatic SKS rifle is also seen carried by Taliban forces. They appear to be of Chinese origin.
A Browning M2HB machine gun is briefly seen mounted in a guard tower in Afghanistan.
What appears to be an FN MAG is manned by a doorgunner on the Black Hawk carrying Capt. Cahill and his Marines.
M203 grenade launcher
The M203 grenade launcher attached to an M4A1 is briefly seen carried by a Marine that rides in a humvee with Capt. Cahill.