Green’s Dictionary of Slang

dog n.5

also dawg
[pun on barker n.1 (4)]

(orig. US) a pistol.

[US]W.G. Simms Forayers 170: The pistols, Carrie, the old dogs!
[US]C. McKay Home to Harlem 287: Guess Billy is right toting his silent dawg around with him.
[US]L. Hughes Tambourines to Glory I vii: I carried a pistol, called it Dog.
67 Beats Cypher‘’ 🎵 44 let me dog bark (drill it drill it drill it) / I said 44 let me dog bark.