Green’s Dictionary of Slang

break v.7

(US) to seize and use a gun.

[US]T.R. Houser Central Sl. 12: break To pull out a gun, usually from some location on the person and use it. ‘This nigger gets in a fight and bleeds, I break.’ break a guage [sic] To have immediate recourse to a tube or shotgun. To seize, rack and use a shotgun.