The Colt 1907 was one of the significant developmental iterations of the design that would eventually be adopted as the Model 1911 by the US military. This pistol began as John Browning’s Model 1900 in .38 caliber, with the .45ACP cartridge being first created for the Model 1905 iteration. That 1907 was the model actually purchased for field trials in the wake of its top placement in the 1907 US pistol trials.
The 1907 differs from the Colt 1905 primarily by its inclusion of a grip safety, added at military request. The trials pistols were evaluated for several years by several Cavalry units as well as institutions like the Army School of Musketry. This period of evaluation would lead to a series of small revision to refine its performance (such as improvements to the sear durability and widening of the ejection port) but there would be one last major design change before the pistol was in its final form. Even while the 1907 was being tested, Browning was working on replacing the twin-pivot locking system with a single-pivot one which would be presented to the Army as the Model 1909.