The only hammerless pump-gun design that predates John Pederson's Model 10 is this one (with it's later redesign below it)
John Browning sold the design for his first hammerless repeating shotgun in 1903 to the J. Stevens Arms and Tool Company in Chicopee Falls, Massachusetts. Called the Model 520, production ran from 1904 thru 1930, with guns continuing to be built on existing parts until about 1932. Stevens/Savage redesigned the gun (to look more like the Model 10 and the Model 12) and came out with the Model 620 in 1927. Production on the 620s was discontinued in 1955. These are both 20s.
