During the final assault, Frank (Ray Stevenson) takes a custom M4A1 Carbine with a red dot sight, a sound suppressor, and a short version of the AG36 grenade launcher. The suppressor is an M4-2000 by Advanced Armament Corp.
H&K AG36 Grenade Launcher
Frank appaently shortens an Heckler & Koch AG36 Grenade Launcher to make it more light weight. Prop wise, this is an airsoft product called the AGX made by Madbull. They have been making reference to its use in the film for some time now.
M203 Grenade Launcher
Frank is seen using this, but it was a stand alone, and apparently the effects guys made it looked like he fired a missile out of it. It was used once before Frank switched to the SL8.
Smith & Wesson 500 Magnum Revolver
Frank Castle keeps a performance center version of the Smith & Wesson Model 500 as one of his sidearms. He has this stainless version with extended ejector shroud and also one with a supressed black barrel and a Knight's Armament RIS setup, flashlight, and laser. A bunch of one of the gangs were given to them, some standard and some with scopes.
Beretta INOX
Frank Castle uses twin stainless Berettas with extended mags and converted to full-auto in the movie. The gun expert for the film claimed to have given him Beretta 92FS for the dinner scene, but it definitely looks like Microchip gave him a pair of INOXs for later scenes.
Beretta M92F
In the hands of one of Jigsaw's thugs and was taken by a cop.
H&K MP5K
Used in the first gunfight scene. They are seen with stainless steel recievers and they have thier foregrips removed,making them true "machine pistols".