A very late entry into the field of First World War fighting shotguns, the Stevens Model 520 Trench Gun was an improvement from a base sporting design created by John Browning, which had a number of virtues for combat work. Browning's core design was rugged and reliable, with an internal hammer to prevent pinching and snagging, and a well-designed takedown mechanism. To this was added a bayonet adaptor and a heat shield, to give the arm a close-combat capacity a standard sporting shotgun lacked. Deviating from the typical layout used by most American trench guns, the Stevens uses a multi-piece adaptor and shield configuration. The bayonet adaptor is configured to both engage an integral barrel lug as well as act as a split clamp around the muzzle, giving it an extremely tight fit resistant to developing play or rotation, with a rifle style blade front sight. The heat shield uses a 3-hole port sequence, with notably smaller holes than the norm, bearing against the same lug as the bayonet adaptor to maintain spacing between it and the barrel. While the 520 Trench made a good impression on the testers, the Stevens offering was too late to be accepted and deployed into the field. The experience wasn't a complete loss, as Stevens would later enter the police shotgun market with the 520, and the government would snatch up the remaining 520s during the crash arming program for World War II. This shotgun features both the adaptor and heat shield on the barrel, with a sling swivel tapped into the barrel lug. The operating rod bears the Stevens trademark and "520", with the three-line Arms & Tool address on the left side of the frame. Matching serial numbers are present behind the trigger guard, on the left side of the magazine tube, and the bottom of the bolt. Fitted with a ribbed forearm and a smooth pistol grip stock, with a flat steel buttplate and a 13 1/2 inch length of pull. Notes from the consignor (no firm documents provided) attribute this shotgun to the family of Mark W. Clark, WWI/WWII/Korea veteran and America's youngest 4-Star General. Among other distinctions, Clark was a signatory of the Korean Armistice as Commander-in-Chief of United Nations Command, was president of the Military College of South Carolina (aka the Citadel), and the head of the "Clark Task Force" on intelligence activities.