David Marshall “Carbine” Williams is best known for his work on the M1 Carbine during World War Two, but he actually worked on several other projects while employed by Winchester, and the Carbine was an unexpected side project. His work began when he was assigned to take over development of Ed Browning’s rifle, which was first produced by Colt in 1929 and then taken up by Winchester in 1938. Browning died in 1939, and Williams was tasked with improving the rifle. He did this by first replacing its gas system with his own tappet system, and then replacing the tilting bolt with a Garand-style rotating bolt. Winchester wanted a self-loading military rifle to market during the war, and it was mostly by chance that they opted to also scale it down for the Light Rifle trials in 1940. After successfully getting it adopted as the M1 Carbine, Winchester and Williams would return to the design in .30-06 as the Winchester Automatic Rifle to compete with the BAR, and in a .50 BMG anti-tank incarnation. Here is information on each rifle along this path:
Colt/Browning 1929
Winchester/Browning G30
Winchester/Williams G30M
Winchester/Williams M2
Winchester/Williams G30R
Winchester Automatic Rifle
Winchester/Williams .50 BMG A-T rifle