The following weapons were used in the film A Bittersweet Life:
Pistols
Stechkin APS
Sun-Woo (Byung-hun Lee) uses a Stechkin APS pistol for much of the latter half of the film, stealing it from a weapons dealer who claims it is the "finest gun manufactured in Russia". Although the Stechkin is select fire, Sun-Woo only fires it in semi-automatic.
Beretta 92FS
During the finale, one of the thugs working for Mr. Baek uses a Beretta 92FS pistol.
Revolvers
Smith & Wesson Model 12
Sun-Woo's friend Min-Gi uses what looks like a Smith & Wesson Model 12 at the start of the film when they both go to confront some of Baek's men.
Smith & Wesson Model 40 Centennial
Moo-Sung is armed with a Smith & Wesson Model 40 Centennial revolver during the finale. Another of Baek's thugs is seen loading one by spinning the cylinder and flicking his wrist to the right in order to push the cylinder back into place.
The gun on the film poster looks like a Smith & Wesson Model 60 and is present in the arms cache when the gun dealer's brother acquires some weapons, though he does not pick it up. Another Model 60 is seen when Sun-Woo collects some guns and ammunition after killing the gun dealers when searching through the bags, and even though he does take it for himself, he never uses it during the finale.
A Steyr SPP, mounted with a front grip and converted to automatic fire possibly to give the appearance of a Steyr TMP, is used by the arms dealer Myung-Gu before Sun-Woo kills him, taking the gun for himself and using it for the rest of the film. Another slightly modified Steyr SPP is used by one of Baek's thugs in the finale, but he is killed by the gun dealer's brother before he can ever fire it.
Assault Rifles
Norinco Type 56-1
Two thugs working for the mobster Mr. Baek use Norinco Type 56-1 rifles during the finale, firing them wildly at Sun-Woo before they are killed.