This is an attractive looking example of a very scarce "U.S." marked Colt Model 1907 semi-automatic pistol that was submitted by the Colt Firearms Company for the U.S. Army "Test Trials" in 1907. This pistol is one of only 205 actual pistols manufactured under the Army Contract of 1907 for field trials. This pistol, serial number 90, was shipped from Colt to the Springfield Armory on March 17, 1908 and was one of the 64 pistols issued to Troop H, 2nd Cavalry Regiment at Fort Des Moines, Iowa for actual evaluation. Due to numerous design and or manufacturing deficiencies found during the initial test firing of the field trials Colt submitted a letter to the Chief of Ordnance requesting to withdraw all of their test samples, agreeing to modify them to correct/improve the initial deficiencies and then returning them to the Army for further evaluations. As noted on page 35 in Clawson's "Colt 45 Service Pistol", this specific example, serial number "91", was one of those withdrawn, modified and reissued for further testing by the 2nd Calvary Regiment, at Fort Des Moines, Iowa. These 1907 "Test Trials" pistols are extremely rare and very important for both the Colt and U.S. Martial pistol collector from two aspects; one, it was the first U.S. Army contract pistol chambered in the newly designed "45 ACP" cartridge. Although replaced in 1985 by the 9mm round for the new U.S. service pistol, this cartridge is still being used by the U.S. military Special Operations Command in several pistols employed today. Two, this pivotal 1907 design and the subsequent modifications lead directly to the development of the all time favorite U.S. Army Model 1911/1911A1 pistol that was in service for over 74 years. This is certainly an extremely important link in any U.S. martial arms pistol collection. The right side of the slide is roll-stamped "AUTOMATIC COLT/CALIBRE 45 RIMLESS SMOKELESS" in two lines, and the left side is marked "PATENTED/APR. 20, 1897. SEPT.9.1902. DEC.19.1905." in two lines followed by "COLT'S PATENT FIRE ARMS MFG. CO./HARTFORD. CONN. U.S.A." The serial number "90" is located on the left side of the frame above the trigger guard bow, which has the initials of Ordnance inspector "K.M." (Major Kenneth Morton). It is complete with an original Colt manufactured unmarked magazine that has the small longitudinal slot on the back side for the magazine catch, desirable in itself.