The Colt Model 1900 was a self-loading semi-automatic .38 caliber handgun introduced by Colt at the turn of the 20th century. It also marked the introduction of .38 ACP, the round for which it is chambered (not to be confused with the smaller .380 ACP). It was developed from John M. Browning's earlier prototypes in the late 1890s. The United States military tested the design against other semiautomatic pistols by European makers, and adopted some versions for trial use. The M1900 and variants were also offered commercially. Variations included the Model 1902 Sporting, Model 1902 Military, Model 1903 Pocket (in .38 ACP; the .32 ACP model was a different design), and the Model 1905, which introduced the .45 ACP cartridge. The designs of 1909 and later did away with the front bushing, and would become the M1911 pistol.

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