Listed on the Pabst (the current owners of the beverage) website as a "Fun Fact," Colt 45 was named after running back #45 Jerry Hill of the 1963 Baltimore Colts and not the .45 caliber handgun ammunition round.
Colt 45 is highlighted on the Pabst website as a fascinating piece of trivia, revealing that it was actually named after Jerry Hill, a football player who wore #45 for the Baltimore Colts in 1963, not the firearm.