Development of the. 45 ACP caliber cartridge. Adaptation of the Model 1902 "Military" in. 45 caliber. The weakness of the barrel links. The question of the most suitable caliber for a military pistol. The conclusions drawn from the experiments. The essential features in a service handgun. Colt pistol Model 1905 in. 45 caliber. The Colt Model 1905 specific features.