The firearms that were seen and used in the Uwe Boll film Postal include the following...
Heckler & Koch G36
Heckler & Koch G36E 5.56mm
Heckler & Koch UMP
H&K UMP45 factory standard model - .45 acp
Heckler & Koch MP7
H&K MP7A1 4.6x30mm with Zeiss Z-Point sight. This MP7 shown in SMG configuration.
Beretta 92FS Inox
Beretta 92FS
Colt Python
FN Minimi
M249-E1 SAW with 200-round ammo drum - First major upgrade of the SAW officially adopted by the U.S. Military (this is a real blank adapted movie gun) - 5.56mm
Remigton 870
Remington 870 Police Magnum with folding stock - 12 gauge
AKS-74U
AKS-74U (also referred to as the "AKSU" or 'Krinkov') - 5.45x39mm
RPG-7
Lee-Enfield No.1 MkIII* rifle
Mosin-Nagant M91-30 rifle
Browning M2
Zavasta M70B
AKMS
Norinco Type 56-1
Jericho 941
Carl Gustav recoiless rifle
M60 machine gun
Ruger Redhawk