M1

There are multiple things with the name "M1":


 * M1 Thompson Submachine Gun, a WWII era American submachine gun
 * M1 Garand, a WWII era American infantry rifle
 * M1 Carbine, a WWII era infantry rifle often erroneously named in-game as M1A1 Carbine, when in fact the only M1A1 appeared in Call of Duty and Call of Duty: United Offensive
 * M1 Abrams, a modern day American tank