The Ithaca Mag-10 is a gas-operated, semi-automatic shotgun chambered in 10-gauge (3½"). It was produced until 1989, at which point Remington Arms bought the design and used it as the basis for the Remington Model SP-10.
A variant featuring a shorter, 21" barrel was created called the Roadblocker. The model was marketed to the law enforcement market, but met with little commercial success.