We’ve had this particular gun listed as unidentified for quite a long time, and had people suggest pretty much everything you can imagine to explain its origins:
Well, thanks to a private collector we visited, we now know what it is. The gentleman had a pile of WWII-era Aberdeen Proving Ground photos which include several shots of this particular gun, including the label information. The gun is a .30 carbine submachine gun invented by George Hyde, and it was photographed by Aberdeen on May 8th, 1944. The gun is particularly interesting for its use of a quick-change barrel mechanism obviously copied off the German MG42:
That’s a totally obvious copy of the MG42 (which had only been around for a couple years), but one really has to wonder why a quick-change barrel would be necessary on a submachine gun. It neat to look at, sure, but how could Hyde conceivably justify the extra manufacturing cost in 1944?
George Hyde is not a well recognized name, but was very active and involved in the American war effort. He was designing submachine guns at least back to 1933, and one of his guns (the Bendix-Hyde carbine) was entered in the Light Rifle trials which would eventually lead to the M1 Carbine.He also had a hand in the development of the Liberator pistol, designed the M2 submachine gun that was briefly adopted as a substitute standard, and designed (in cooperation with Inland’s Frederick W. Sampson) the M3 “Grease Gun” that replaced the Thompson in US military service. Quite the prolific designer! Unfortunately, no known examples of this gun remain in existence.
You can see all of the Aberdeen photos of his 1944 design here (download the gallery as a high-res archive):