Colt .45 was part of the William T. Orr-produced array of Westerns which Warner produced for ABC in the late 1950s and early 1960s.
Colt .45 also featured fictionalizations of actual historical characters, including Edwin Booth (brother of John Wilkes Booth, the assassin of U.S. President Abraham Lincoln), Sam Bass, Billy the Kid, Lew Wallace, Judge Roy Bean, Buffalo Bill Cody, Ned Buntline, and Calamity Jane.
[3] Due to the casting changes, the series was eventually marketed in the United Kingdom as The Colt Cousins.
According to author Alvin H. Marill, the choice to cast Donald May in the lead role after Preston's departure was not explained in the storyline.
The Colt .45 opening theme music was composed by Hal Hopper with lyrics by Douglas Heyes.