Early in the movie, when the babies are being chosen for the Adam program, armed guards can be seen in the nursery armed with M16-type rifles. The weapons are not seen clearly, but are most likely M16A2s.
During the training phase, several Humvees can be seen, each with an M60 machine gun mounted on the roof.
During the training phase, the child recruits can be seen firing 1st generation M4A1 Carbines fitted with C-More red dot sights and RIS foregrips.
The cruel and cowardly commander of the soldiers, Colonel Mekum (Jason Isaacs) can be seen carrying a nickel-plated Colt Single Action Army with pearl grips as his sidearm, using it to shoot first one of the older soldiers injured in the fight with Caine 607 (Jason Scott Lee), one of the newer soldiers, and then Captain Church (Gary Busey) when he refuses to follow orders.
The standard-issue assault rifles of the soldiers throughout the film, including Sergeant Todd (Kurt Russell) and later the super-soldiers, are modified Century Arms AK-47 bullpup rifles made to look futuristic. The weapons have been given extended barrels and shrouds that appear to have been borrowed from Franchi SPAS-12 shotguns. Additionally, the rifles have C-More red-dot sights, dual retractable bayonets, and tactical flashlights. In some scenes, the rifles feed from standard 30-round AK "banana"-style magazines (this is most obvious during a flashback when Sgt. Todd is seen reloading and his magazine is shown hitting the ground), while in other scenes, they are fitted with 100-round drum magazines.
A soldier is shown firing his assault rifle during the scene where the old and new soldiers compete against each other. This shot clearly shows that the weapon is a Century Arms bullpup AK. The shape of the AK receiver, selector, and bolt carrier is clearly visible, while the distinctive vented housing over pistol grip identifies the weapon definitively as a Century Arms gun
During the "War of the Six Cities" flashback to Sgt. Todd's earlier days an enemy soldier is seen armed with a rifle which is definitely a Heckler & Koch G3 variant. It's not seen clearly, but looking closely, it is possible to see that that the rifle lacks the flipper magazine release of the original H&K G3, which means that it is almost certainly a civilian HK91 standing in for the mil-spec G3.
During the montage showing Sgt. Todd's service following his training, a combatant in the "Moscow Incident" can be seen brandishing a Heckler & Koch MP5A2 while holding a civilian woman hostage, Todd shooting both the enemy and the civilian with no regard for civilian casualties.
During the flashback to the "Battle of the Argentine Moons", Sgt. Todd is using a pair of nickel-plated Franchi LF-57 submachine guns with the stocks removed and some type of old-fashioned tube sight installed on top.

http://www.megavideo.com/v/3QAQQA9202bc2ada6e7536837924e638fc713aed