Produced at an unknown time with fixed sights, no maker's marks on the slide, and the frame stamped "RAD" over the magazine catch. The RAD marking stood for Colt's Research and Development department, where the factory conducted their experimentation with various models of guns. Checkered walnut grips, wide hammer, short trigger, checkered slide catch and thumb safety, long grip safety, and smooth arched mainspring housing with lanyard staple, flattened and cut for a shoulder stock. The pistol has a small brass inventory tag numbered 638. This pistol is documented on page 224 of "U.S. MILITARY AUTOMATIC PISTOLS 1920-1945", by Scott Meadows.