This experimental prototype falls 69 digits ahead of the factory prototype featured in our December 3, 2016 auction and has some of the same basic design elements but differs in many of the smaller component. It has a threaded and ported vent rib barrel with grooved sides, blade and adjustable notch target sights, target grips with "MAY 58" on the inside, "GX 4301" on the right side of the frame, and "COLT CAL. .22 L.R." on the magazine. The factory letter confirms this pistol is an experimental prototype and notes the putty on the grips is from "experimenting with contours."