The Stevens Model 520 was a pump-action shotgun developed by John Browning and originally manufactured by the J Stevens Arms & Tool Company between 1909 and 1916. Stevens was sold to New England Westinghouse on 28 May 1915 and production of civilian firearms was greatly reduced. The company was renamed the "J Stevens Arms Company" on 1 July 1916 and New England Westinghouse used their manufacturing facility in Chicopee Falls, MA to produce Mosin-Nagant rifles under contract for the Russian Czar during World War I. After the war, Stevens was sold to Savage Arms on 1 April 1920 and full production of civilian firearms resumed. Under Savage ownership, Model 520 production continued until 1939 when it was replaced by the Model 520A which ended production in 1948. Stevens also further modified the design when they introduced the streamlined Model 620 in 1927. The Model 620 was internally similar to the Model 520 and was produced until 1939 when it was replaced by the Model 620A which ended production in 1955. This shotgun is a hammerless, pump action, take-down design with a tubular magazine which holds 5 shells. All models can also be slam fired: the shotgun has no trigger disconnector and shells can be fired one after the other simply by working the slide if the trigger is held down.
The first Stevens 520 appeared in Stevens' 1909 Catalog No. 52 and was also offered for sale in the fall 1909 Sears & Roebuck catalog. It is easily recognizable by its "humpback" double receiver. It has a round slide release knob on the left side of the receiver, a visible breach locking bolt on the top of the receiver, and base models have a rounded pistol grip on the buttstock. The foregrip is ringed and uniform in size. The trigger housing is retained with three screws and the safety is a lever located inside the trigger guard in front of the trigger. The cartridge stop is a rocker design with a set screw on the front right side of the receiver. There were other models including a Model 522 trap gun and the 525, 530, and 535 with increasing levels of engraving and stock quality (some straight grip) and foregrips. Internally there is an inertial slide release block that is affixed to the inside of the receiver. This inertial release uses the recoil of a discharged round to unlock the breech. The action was designed to only unlock after firing or with the use of the slide release and not by dry firing like many modern shotguns. All model 520s were only offered in 12 gauge until 1928.
The receivers of both models were stamped on the left side (from front to back) with a small "P" and ordnance bomb, "Model 520-30" or "Model 620", and a small "U.S." over the trigger. Model 520-30 trench gun barrels are marked "Proof Tested--12 Gauge --2 3/4 Inch Chamber--" on the left side and have another small "P" and ordnance bomb and the "J Stevens Arms Company" address on the right side of the barrel. This was done so that all the markings could be read with the heat shield installed. Some Model 620 trench gun barrels were marked in the same manner as the Model 520-30 trench guns and some had all the barrel markings on the left side. Trench guns were also fitted with a sling swivel in the stock. Riot guns also had 20-inch barrels (cylinder bore) and had all the same martial markings, except that all the barrel markings were on the left side. The long-barreled training guns were marked in the same manner as riot guns and were mainly used for aerial gunnery training. Total wartime production of all Model 520-30 shotguns was 33,306 and all Model 620 shotguns were 12,174. 2b1af7f3a8