Caliber Conundrum

In 1873 the United States military had adopted the Colt Single Action Army .45 Colt. This big sixgun served them well on the frontier but in the 1890s the military took a huge backward step — mothballing the big .45 SAA in favor of a double-action Colt pistol chambered in .38 Long Colt. When this proved inadequate in combat in the Philippines, the old .45 SAA was quickly pressed back into service. The Army apparently had learned its lesson and they called John Browning before a review board to ask if he could come up with a semi-auto pistol larger than .39 caliber.

His first attempt was the Model 1905 chambered in .45 ACP. The government liked what it saw and scheduled testing to adopt a new pistol in March 1911. Browning worked with the engineers at Colt to get his design ready and the necessary changes were made, resulting in what we know today as the 1911.