When the US military held its automatic pistol trials in 1907 (actually beginning in December 1906…), Colt submitted a Model 1905 pistol. Despite what would be considered today to be significant problems, it was judged one of the best guns tested. A few changes were requested (more vertical ejection, a loaded chamber indicator, and a grip safety), and Colt was contracted to make 200 guns for a year-long field trial. Those guns would be the Model 1907, and they were issued to Cavalry units in Iowa, Minnesota, and the Philippines for an extensive trial.

The trial results were actually pretty poor. Unit commanders complained of significant jamming problems, broken parts (mostly firing pins and sears), difficulty getting accurate fire, and awkward handling on horseback. These issues were partially alleviated by a few modifications made to the guns in the latter half of 1909 (larger ejection ports and larger grip safeties, primarily). Ultimately, however, John Browning’s continued developmental work during the course of the field trial would result in a substantially improved mechanical design for the gun…