The Ingram Model 5, marketed as the Lightning Model 5, was an American submachine gun designed by Gordon B. Ingram.
The Model 5 was Ingram's first weapon design upon returning to the United States after World War II. He chose the name "Model 5" to avoid confusion with the US Army's existing M1, M2, and M3, and to allow for a possible M4. The weapon was marketed by the Lightning Arms Company and offered for military sales. The Nicaraguan Army arranged tests for the weapon, overseen by Ingram. However, despite some interest, no orders were placed. Owing to a lack of sales, Ingram abandoned the design and instead focused on the development of his next weapon, the Model 6. Only one prototype of the Model 5 was ever built.
The Model 5 was a very basic blowback-operated submachine gun. The only moving parts were the bolt, trigger, and sear. It used a loose firing pin that was permanently protruding from the bolt. The rear end of the bolt was hollowed out to reveal the back of the firing pin, which the return spring pressed directly onto. The body of the weapon was largely comprised of light steel components with some wooden furniture. The sole prototype used 12-round Reising magazines, but it was intended to be produced with 25-round magazines.