The US military did use shotguns during World War II. The most common shotgun used by the US military during World War II was the Winchester Model 1897. This pump-action shotgun was chambered for the 12-gauge shotgun shell and had a capacity of five rounds. The Model 1897 was used by the US Army, Navy, and Marine Corps during World War II. It was primarily used for close-quarters combat, such as trench warfare and urban fighting. The Model 1897 was also used by the US military during the Korean War and the Vietnam War.