A Beretta 92FS is used by Big Daddy (Nicolas Cage) in an early scene to shoot his daughter Hitgirl (Chloe Moretz) to show what is like to be shot with a bullet proof vest on, and later when he attacks a group of mobsters at Frank's Lumber warehouse.
A mobster guarding Frank D'Amico's apartment in the finale is armed with a Glock 17.
Heckler & Koch USP
One of D'Amico's men is armed with a Heckler & Koch USP (of unknown caliber, probably .45 ACP) during the final shootout at D'Amico's home.
Heckler & Koch USP Compact
A Heckler & Koch USP Compact is wielded "akimbo"-style by Mindy Macready aka "Hit Girl" (Chloe Moretz) along side a SIG Sauer P232 (left hand). A two toned H&K USP Compact is wielded by a thug. She also uses one in the POV scene and during the rescue.
SIG-Sauer P220
One of the mobsters guarding Frank D'Amico's apartment is armed with a SIG-Sauer P220.
SIG-Sauer P226
One of Frank D'Amico's men is armed with a SIG-Sauer P226.
SIG-Sauer P232
Hit Girl uses a SIG-Sauer P232 during the shootout at D'Amico's home. Hit Girl reloads the P232 by dumping the magazine with only one hand, which is impossible because the magazine release is located at the heel of the grip.
Shotguns
Mossberg 500
Damon Macready aka "Big Daddy" seizes a Mossberg 500 shotgun with an extended magazine tube from one of Frank D'Amico's men and uses it during the gunbattle at Frank's Lumber warehouse.
Armsel Protecta
A heavily modified Armsel Protecta is used by one of the mobsters shooting at Hit Girl during the finale. It differs from most examples of the weapon due to having a muzzle brake, a M1913 rail over the drum and the back half of the weapon modified to take a M4 style stock.
Sub-machine Guns
Heckler & Koch MP5K
A Heckler & Koch MP5K is fired by one of Frank D'Amico's men at Hit Girl during the execution rescue scene. Hit girl is also seen loading and pointing one, with a 15 round magazine, at Kick-Ass in the Mcready's armory before placing it in her tote-bag prior to the assault on the D'Amico's penthouse (it's never seen again).
Two L85A1 with SUSAT scope are seen in the Macready's arsenal.
M4A1 Carbine
Several M4A1 carbines with scopes and foregrips are seen in the Macready's armory.
SIG SG552
SIG SG 552 rifles with scopes and foregrips are seen among the weapons in the Macready's armory. Later, a mobster wildly fires a SG 552 at Hit Girl when she attacks Frank D'Amico's apartment.
Steyr AUG
A Steyr AUG is also among the many weapons seen in the Macready's arsenal.
Unknown Sniper Rifle
Damon Macready aka "Big Daddy" uses a suppressed sniper rifle of unknown make to cover Hit Girl during the fight at Rasul's (Kofi Natei) apartment.
Heavy Weapon
GE M134 Minigun
Dave Lizewski aka "Kick Ass" uses two GE M134 miniguns mounted on a jetpack during the finale. These appear to be based on the short-barreled version.
Mk 153 Mod 0 SMAW
A Mk 153 Mod 0 SMAW, referred to throughout the movie as a "bazooka", is used by Huge Goon (Stu Riley) during the finale. The trigger/firing mechanism looks very odd on the Mk 153 used in the movie. It looked like it had the frame of a H&K MK23 pistol mated to the lower receiver of a H&K MP5 sub-machine gun.