Officers of the Los Angeles Police Department are mainly seen armed with Beretta 92FS handguns as their sidearms during the bank shootout.
Glock 17
One of the LAPD officers is seen firing a Glock 17 during the bank shootout.
SIG-Sauer P226
An LAPD officer is seen with a SIG-Sauer P226 during the bank shootout. A criminal during the credits is also seen with a SIG P226 and uses it to hold a woman hostage before Hancock intervenes.
Not sure about the LAPD officer's gun, but the criminal (who is played by Mike Epps) is using a P228. The barrel is too short to be a P226, plus it has the rounded trigger guard (P226 would be squared/pointed).
Remington 700PSS
LAPD snipers use Remington 700PSS rifles during the bank shootout.
Brügger and Thomet MP9
One of the Asian gangsters during the freeway chase is seen using a Brügger and Thomet MP9 to shoot at the cops. He tries to shoot Hancock (Will Smith) with it but the bullets deflect off his skin and break his liquor bottle, which angers him enough to apprehend him and his friends.
Cobray M11/9
A Cobray M11/9 is used by one of the Asian gangsters during the freeway chase. He tries to shoot Hancock with it but the bullets deflect off him.
Not true; the Cobray, unlike the MAC-10 that it was based on, fires from a closed bolt.
M4A1
LAPD SWAT officers and standard officers are seen using M4A1 rifles fitted with ACOG scopes and Surefire M900 tactical lights. One of the bank robbers is also seen using an M4A1, his fitted with an A.R.M.S. selective intergrated rail system and tactical foregrip/light hybrid.
Can't be an M4 if its barrel is that short. Probably some other AR-knockoff.
Heckler and Koch G36K
One of the bankrobbers is seen using a Heckler & Koch G36K during the bank shootout.
An unknown MGL Grenade Launcher is used by one of the bankrobbers to shoot at Hancock, but the rounds deflect off his skin.
Special
Barrett M82CQ Custom
A Barrett M82CQ converted to full auto and fitted with an extended magazine is used by one of the bankrobbers during the shootout. The officers on the scene refer to it as "heavy artillery, possibley .50 caliber or bigger", apparently bigger according to the armorer. Due to the recoil emitted by a handheld full-auto .50 caliber, the bipod has to be used as a foregrip.
Can you tell if it was actually converted to auto, or if the sound editor just added full-auto sound effects?
Special
Heckler & Koch UMP
One of the criminals in the hospital trying to get revenge on Hathcock fires at him with a Heckler & Koch UMP.
FN FAL Carbine
One of the criminals in the hospital trying to get revenge on Hathcock fires at him with a FN FAL Carbine, likely a DSA SA58 OSW.