This is a solid example of a very early Colt Service Model Ace 22LR pistol with serial number "SM224". these pistols were developed in the late 1930s to duplicate the weight, feel and recoil of the Model 1911A1 pistol while firing the economical 22LR cartridge. This pistol was manufactured in 1937, the third year of production (only 50 were produced in the previous 2 years). These early issue pistols are very rarely found as most saw extensive use. The left side of the slide is marked with the Colt two line address of "COLT'S PT. F.A. MFG CO. HARTFORD CT. U.S.A. / PAT'D APR. 20. 1897, SEPT. 9. 1902, DEC. 19. 1905, FEB.14. 1911, AUG 19. 1913." followed by the Rampant Colt. The right side of the slide is marked "COLT / SERVICE ACE (inside the a diamond) 22 LONG / RIFLE / MODEL" The right side of the frame is marked "SM224". It is fitted with the early screw adjustable rear sight and the magazine is marked "COLT / 22 ACE L.R. / SERVICE MODEL". It has the checkered arched main spring housing and early Colt wide checkered hammer, and is fitted with checkered walnut grips. The accompanying factory letter verifies the serial number, caliber, barrel length, blue finish with grips as "Not Listed" and that it was shipped as 1 of 155 to the United States Government, Springfield Armory, Springfield, Massachusetts on July 20, 1937.