Most of Ammo's early history was unrevealed. It was known that he served in Vietnam, and possibly acquired his love of violence there. He surfaced as a leader of a large, vicious street gang in the Hell's Kitchen slums of New York City.
Ammo took advantage of a power failure (caused by the mutant hero team X-Factor fighting the villain Apocalypse) and claimed it was a sign of humanity's collapse. He led his gang (which included the street thugs known as the Wildboys) on a rioting spree, and managed to raid a US armory. Hoping to raid a hospital's drug supply and eventually become a powerful post-apocalyptic leader in New York, he and his gang were stopped by the hero Daredevil and imprisoned.
Ammo was rescued from prison by Daredevil's enemy, Typhoid Mary, who asked for Ammo's assistance in a complex plan to kill Daredevil. Ammo readily agreed and beat Daredevil severely during a series of battles orchestrated by Mary, before leaving Daredevil in Mary's hands.
Presumably, Ammo returned to lead his gang, and remained at large.
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