This rifle was designed by Winchester and submitted for testing by the US Marine Corps in 1940. The Marines had not adopted a semiautomatic rifle, and ran an exhaustive competitive test between the bolt-action Springfield, the Johnson, the Garand, and this Winchester design. The Winchester was a sleek and lightweight rifle, operated by a gas piston which moved only a tenth of an inch upon firing. The piston was located only a few inches forward of the breech, allowing a short and light operating system.
Ultimately the Marine Corps chose the Garand rifle for its reliability and durability, but the Winchester would go on to be an important foundation of the company’s later M1 Carbine design.
I have a book about winchester firearms
has a yellow cover, anyways in the book was an expermential assault rifle from 1917 period that is light years ahead
in terms of design than any thing you have posted, it had dual magazines and was chambered in .351 winchester, in fact
this weapon looks like it could have been designed today