When the U.S. Marine Corps purchased 1,300 Model 1909 New Services revolvers in the 23,101 to 26,300 serial number range from Colt through the Navy Department beginning in May 1909, Colt also made an additional 50 extra frames to the Marine Corps pattern, possibly to replace intended losses or for individuals sales. These extra frames feature rounded and narrower butts, absent Marine Corps service numbers, and a "Square" mark proceeding the 1 through 50 number marked on the frame with this example being number "46". Dubbed U.S.M.C. "Square" Frame New Service revolvers by collectors, these extra frames were later built up by the factory into completed guns in the 1930s and sold off through normal commercial channels, as discussed on pages 70, 140, and 141 of "Colt's New Service Revolver" by Mullin. Features fixed blade front and notch rear sights, the two-line Hartford address on top of the barrel with "COLT D.A. 45" on the left side, absent Marine service number on the bottom of the grip frame with retained "U.S./M.C./No", and "Rampant Colt" backed by a stylized "C" on the side plate. The serial number "square 46" is marked inside the crane well of the frame, with the crane numbered to a revolver from 1911 manufacture. Fitted with a pair of diamond pattern checkered walnut grips number "31" on the interior. Includes a web lanyard.

Fine as manufactured for the Marine Corps contract and subsequently built into a completed revolver by the factory decades later, retaining 60% plus original blue finish on the balance with smooth grey/brown patina, freckling, minor spotting, minor pitting on the grip straps, a cylinder drag line, and light handling wear. The replacement grips are excellent with crisp checkering. Mechanically excellent.