The Winchester-Williams anti-tank rifle is an American prototype anti tank rifle.
The weapon was developed in 1943, and put forth in 1944. When made, the United States military felt like they did not need an anti-tank rifle since they had recently acquired a few Boys anti-tank rifles from John Inglis and Company in Canada, enough to take care of their needs. However, certain claims said that the weapon was also tested on Canadian grounds, despite the Inglis Company already producing the Boys anti-tank rifles. During the tests, the rifle performed very well, as the rifle was semi-automatic and used the standard .50 BMG cartridge that the Canadian military had plenty of. However, before the rifle could be adopted, the entire program was cancelled due to the end of World War II. It is suspected that only one of these rifles was made.