Badge 373 (1973)

"A gun in his sock, a tire iron in his belt, and no badge. The story of Eddie. The best ex-cop in the business."

When his partner is killed, tough Irish detective Eddie Ryan vows to avenge the death, whatever the cost. As he begins unraveling clues, his behavior becomes so outrageous that he's obliged to turn in his badge, but the experience only emboldens him. Ryan eventually learns that his partner was caught up in a Puerto Rican gun-running scheme masterminded by a crook named Sweet Willie, who wants to foment revolutionary war.