Revolver
Rubbed
roscoe
A 'gat'.
rod, gat (short for Gatling gun) -- edit -- htd (heat running device) -- edit -- htd is not a 'word' as the question asks for.
Get gnu gun, guy!
Sten submachine gun
MACHINE GUN KELLY was one of the most famous GANGSTERS.
ruger
rod
over and under
rifle
Sten (British submachine gun).
there isn't one.
salvo