Gallo earned his nickname in mafia circles because he was a ruthless killer who was a happy shooter and very unpredictable. In the late 1940s and 1950s, he tried to overpower mafia boss Joseph Profaci and his crime family to obtain power over New York's streets. Gallo was helped in this war by his brothers Larry and Albert. Albert was himself nicknamed Kid Blast.
Later, Gallo also tried to battle against Joe Colombo and the Colombo crime family. Gallo was one of the first mafiosi to predict a shift of power in the New York streets from the Italian mafia to black gangs, and he started becoming friends with members of the black gangs.