I didn't know about this 1 of 1 Prototype Designed and made by George F. Grebey who worked on the Winchester Carbine rifle design. I wonder what it sold for.
Below is a copy / paste from the 2012 Auction description:
Prototype or inventors model .30 caliber carbine pistol marked “Designed – Made by George F. Grebey, Sept. 1 1943” on butt and right side of frame marked “30 cal. short-semi-auto, -gas action-“. Grebey worked for Winchester and was involved in the engineering and manufacture of the M1 Carbine. This pistol version was made during the Second World War and Grebey hoped to secure a government contract for paratrooper or Special Forces use. The prototype measures 14” overall with 6” barrel, is finished in the bright and shows a left hand carbine style cocking lever with a feeding port that accepts M1 carbine magazines. The pistol is contained within a handmade case with many accessories, extra barrels and gauges. The metal is in the bright and pistol is unfinished with a set of blueprints and working diagram. Recently discovered in the possession of Grebey’s descendents. A rare and museum quality prototype. Should be further researched as it may have ties to Winchester or development for the war department. Est.;$10,000-$30,000.
Auction Link: Prototype or inventors model .30 caliber carbine pistol marked “Designed – Made by George F. Grebe