"The Stevens Model 520 is a classic design from the master himself, John Moses Browning. Browning's Patent Number 781,765 was filed for on 10 July 1903 and granted on 7 February 1905. The design is an artifact of the shift in sportsmen's tastes from single shots and double barrels to the new magazine repeaters, both pump and lever action, from any number of manufacturers. The old J. Stevens Arms and Tool Company of Chicopee Falls, Massachusetts had a history since 1864 of producing successful single shot and double barrel shotguns, and they wanted to get on board the burgeoning pumpgun movement too.
So the company bought the manufacturing rights to the new design from JMB in the spring of 1903, and the Stevens Model 520 entered the marketplace early in 1904. It would stay in production until the similarly-designed but more streamlined Model 620 completely supplanted it in 1932.
The Model 520 has a long history as a fighting shotgun. The history of Stevens fighting shotguns goes back at least to the days when a Stevens-manufactured Wells Fargo 'messenger gun' was used by Wyatt Earp to kill "Curley Bill" Brocius at Iron Springs (now Mescal Springs), Arizona in the aftermath of the famous gunfight at the O. K. Corral.
At the request of the War Department when the US entered World War I, Stevens submitted a prototype trench gun based on the Model 520 sporting shotgun. The prototype's 20" cylinder bore barrel was outfitted with a Stevens-made bayonet adapter and a perforated sheet-metal barrel shield necessary when using a bayonet mounted on a hot-barreled shotgun.
The early 520s featured the 'humpback' receiver typical of the Browning Auto 5 shotgun, plus an additional "step" machined into the top of the receiver profile. Later 520s had a straight profile to the top of the receiver. Also, the early 520s had the old style Browning 'suicide safety,' a sliding safety bar set into the front of the trigger guard and protuding inside, that had to be pushed forward to fire and slid back to safe.
The military version of the Model 520 made a good impression on the War Department, but it arrived on the scene too late to really compete with designs from Remington and Winchester. Still, it is believed that a small number of Model 520 Trench Guns were delivered to the War Department before the Armistice was signed. With the Armistice, all military contracts were cancelled.
The Model 520 is indeed a robust design. The receiver itself is machined from a solid steel drop forging. Since the hammer is enclosed within the receiver, there are no protruding snags to hang up on anything. On later production Model 520s, the safety is a top tang sliding button. There are also some Model 520s with a crossbolt safety behind the trigger as well. The action release button is inset on the left rear of the trigger guard. Thses control locations make it lefty-friendly, though the ejection port is on the right.
The bolt is locked into a cut through the top of the receiver by Browning's rising lug locking system. The locked lug is easily visible and locked status can be determined by touch as well, feeling for the locking lug level with the top of its recess. The bolt is designed with a safety interlock that keeps the gun from firing unless the bolt is fully forward and locked. As is common with designs of this vintage, the Model 520's fire control system does not include a disconnector- the Model 520 too can be slam fired, like the Winchester Model 12 and the Ithaca Model 37. I say this NOT to encourage such shenanigans but as a warning to those unfamiliar with designs of this sort. If your safety consciousness and trigger finger discipline are not up to snuff, you can easily ND (negligently discharge) a shotgun which lacks a disconnector. It happened to a State Trooper who had borrowed one of "my" PD's two Model 12 Riot guns one night on a raid on a shothouse (an illegal drinking establishment). Upon entering the premises being raided, the trooper racked the Model 12 and simultaneously blew a hole through the ceiling with a load of 00 buck. In this case the mythical sound of a pump shotgun being cycled DID have its legendary effect- there wasn't an intact window left in the place as the startled inhabitants of that den of iniquity leaped through every available opening to escape. I still think the roar of that round of buckshot going off had a lot to do with it though
. Fortunately the ceiling and the roof (not to mention the windows) were all that suffered.
Given that the locking lug and its recess are among the most stressed areas in any given shotgun, insetting the locking recess into the receiver top is a familiar weak point in repeating shotgun designs of this vintage. The famous Winchester Model 12 design suffers the same weakness, with the rear of the bolt locking into a recess in the top of the receiver, and wear is reflected in increasing headspace. Both receivers and locking lugs are subject to significant wear over many thousands of rounds fired, and repairing wear damage to the receiver requires significant surgery on the part of a gunsmith.
The wooden forearm of the Model 520 is pressed onto the metal tube that is in turn attached to the single action bar that runs on the left side of the action. This action bar is a robust piece of steel, despite its double-dogleg bend where it attaches to the forearm. The action parts are almost all machined steel parts or tempered flat springs typical of the era.
The action is designed so that a forward impulse on the forearm as supplied by recoil is necessary to unlock the bolt upon firing. In a properly timed Model 520, pulling back on the forearm while pulling the trigger will not allow the action to unlock- the forearm must move forward a fraction of an inch to unlock the action.
The takedown system on the Model 520 is intriguing. Designed similar to the system used by Andrew Burgess ( http://www.shootingbums.org/hvr/burgess.html
), the system utilizes a series of engaging ribs and grooves in the receiver and barrel/magazine block. The whole thing is locked in place by the threaded magazine tube, which when tightened holds a pair of wedges into V notches in the side of the receiver when the magazine tube is screwed back into place.
The brief venture into supplying fighting shotguns to the War Department for WWI had a lasting effect on Stevens, and the company continued to supply guns to the police and security market. Even after Savage acquired the entire capitol stock of Stevens in 1920, the production of fighting shotguns as well as sporting arms continued apace.
But competition from other pumpgun designs was having an effect. Winchester's streamlined Model 12 was an attractive and popular design, as was Remington's Model 10. The Stevens Model 620 was introduced in 1927 to compete with these modern-looking shotguns. Internally, the 620 was essentially identical to the 520. But the production of the svelte new model didn't completely eclipse the 520 until five years later in 1932. Model 520s were still being warehoused until then.
In the frantic era of rearming after Pearl Harbor, all of Stevens' warehuse repeaters- including the Model 520s- were purchased by the War Deprtment. They were considered standard military shotguns until 1943, despite the shortage of spare parts available from the factory. Some of these shotguns were equipped with the trench gun bayonet adapters. About 35,000 Model 520s wore the US and flaming bomb ordnance marks during WW2.
After WWII ended, many of these guns went back to the arsenals. Some of them later found their way to participation in the conflict in Southeast Asia."
From the highway. org