In December 1944, the Haenel company received permission to produce a simplified version of the StG-44 Sturmgewehr. The idea was to keep the mechanical system and controls as similar as possible to the design in use, but simplify the design to reduce the cost and time of production. The design was never completed, and this is the only known surviving prototype. It was most likely captured by American forces when they occupied the Haenel factory in April 1945, although that is not documented. It is a pretty impressive adaptation of the StG design; far simpler to manufacture than the original design. Would it have worked? We don't know for sure as there are no known German or American test reports, but it certainly seems viable to me.

Thanks to the Springfield Armory National Historic Site for giving me access to this truly unique specimen form their reference collection to film for you! Don't miss the chance to visit the museum there if you have a day free in Springfield, Massachusetts:
https://www.nps.gov/spar/index.htm