Green’s Dictionary of Slang

bang v.2

also bang off/up
[noise of the weapon]

(US) to shoot; to kill by shooting.

[UK]W. Scott Old Mortality in Waverley II (1855) 425: It’s not easy to bang the soldier with his bandoleers.
[US]R.M. Bird Nick of the Woods I 24: Bang away you big fool, and don’t stand talking.
[US]W.H. Thomes Bushrangers 288: ‘And yer vont shoot at me?’ ‘Not while you are talking with us.’ ‘Vell, then I vont bang at you.’.
[US]Nat. Police Gaz. (NY) 4 Oct. 4/2: ‘I drew my revolver and fired [...] I ran up and banged her again and that was the shot that killed the G—d d—n b—h’.
[UK]Boy’s Own Paper 10 Nov. 91: I banged at him with both barrels.
[US]B. Cormack Racket Act II: Afraid the witness’d get banged, uh?
[US]J. Callahan Man’s Grim Justice 85: I whipped out my gun and fired [...] They banged away at me.
[US]J. Lait Gangster Girl 103: Anybody I can’t jack up I can bang off.
[US]Ersine Und. and Prison Sl. 16: bang, v. (off). To shoot.
[US]C.S. Montanye ‘Frozen Stiff’ Popular Detective Mar. [Internet] He banged away from that ambuscade, getting in a couple of lucky shots.
[US]Goldin et al. DAUL 22/2: Bang, v. 1. To shoot.
[US]Source Aug. 96: ‘A nigga banged me up two or three times.’ [...] Rumor mill has it that the dude shot six times and then realized that you weren’t the person he was gunning for.