Remington Model 31

While the Remington Model 17 enjoyed some success, a solid, 12-gauge featuring side-ejection was needed to compete with Winchester. C.C. Loomis sized up the Model 17 and adapted it for side ejection. The Model 31 was Remington's first side ejecting pump-action shotgun. Stocks were walnut with checkered walnut forend and later changed to a ribbed forend. The Model 31 was made in three gauges with 121,000 12-gauge models made and 75,000 16- and 20-gauge examples also produced. The Federal Bureau of Investigation acquired one Model 31 per office in 1935 in response to the Kansas City Massacre.[3] The model 31L was a lightweight version featuring an aluminum receiver and trigger housing.

During World War II Remington produced a Model 31 riot gun for military use. These were stamped "U.S. Property" on the left side of the receiver and had an approximate serial number range of 51000-63000. Except for a single prototype, no Model 31 trench guns were produced.[4]

Despite being well received, sales still lagged far behind the Winchester. Remington went back to the drawing board and designed the Model 870; this shotgun matched the durability of the Model 12 at a significantly lower cost. Despite the overwhelming success of the 870, many shotgun connoisseurs consider the Model 31 to be the ne plus ultra of pump shotguns with its "ball-bearing" slide action.[5]

The Model 31 was later used as a basis for the Mossberg 500 and related shotguns. The Mossberg is simplified and cheaper to produce. Notable differences are the use of a two-piece bolt with separate locking piece as well as a significantly simplified barrel mounting system. Further, the bolt locks into a barrel extension rather than directly to the receiver.