Action: Semi Auto - Caliber: .45 ACP - Capacity: 20/50 - Finish: Black - Stock/Grip: Fixed Walnut - Sights: Blade/Adjustable - Barrel Length: 16.5 - Overall Length: 41 - Weight: 13 lb - All the classic details of the time honored original are reproduced in today's semi-auto Thompson. The frame and receiver are machined from solid steel or aluminum. The wood is genuine American walnut. This .45 caliber carbine features a 16 1/2 finned barrel compensator and is available with a blued steel receiver or a lighter weight aluminum receiver. This configuration is our most popular model.