The Winchester Model 12, was for years the most popular shotgun in the United States. Over 2 million rolled off the assembly line before 1964. It saw extensive military service in the both World Wars, Korea, Vietnam and didn't leave service until the 1970s. It was a popular hunting shotgun, and many are still in use today. The introduction of the Remington Model 870 forced Winchester to produce cheaper shotguns and discontinue the Model 12 in 1964.