In July of 1910, a special grip was requested by the ordnance department, the main feature of which being a smooth right panel which slightly swelled into the palm. Browning believed this was due to the piece being made too thin and of inferior steel, an issue that could easily be remedied. It still wasn't perfect however, as Browning had to straighten the recoil spring retaining piece multiple times, and it eventually broke completely. The second test occurred five days later, with the pistol operating much better this time, only having one misfire in 1,000 shots. Even with all of these 'improvements', the pistol failed it's initial test fairly miserably, jamming seven times in the first 157 shots, and John Browning withdrawing it from the test to try to improve the design. Penfield described the 'improved model' as having a more simple mainspring cap, smaller, and attached to the spring, extractor inside the breech, ejector made square, angle of the grip changed, the sear, trigger, and grip safety springs made in one piece, butt of the grip sharply angled instead of rounded, barrel slightly lowered, and the ejection port slightly enlarged. They were initially submitted for testing on 9 February 1910, when Captain Walter G. These pistols were initially manufactured to be an improvement upon the 'straight-gripped' Model 1909. military Colt automatic pistol collections. There were reportedly 12 Model 1910 pistols manufactured, making them incredibly rare and often a missing piece in U.S. Originally manufactured in 1910, this is an example of the extremely rare Colt Model 1910 pistol, an extremely important evolutionary piece in the story of the eventual adoption of the Model 1911 by the U.S.

Colt pistol serial numbers