Mossberg 940

About the Mossberg 940

The Mossberg 940 is a gas-operated semi-automatic 12-gauge shotgun and the foundation of O.F. Mossberg & Sons' modern self-loading shotgun platform. Debuting at the 2020 SHOT Show with the competition-oriented 940 JM Pro -- developed in collaboration with champion speed shooter Jerry Miculek -- the 940 introduced a redesigned, self-regulating gas system in which the piston rides over the magazine tube rather than using the older pusher-rod arrangement of the Mossberg 930. Key internal components including the gas piston, magazine tube, hammer, and sear are nickel-boron coated, allowing the action to run up to 1,500 rounds between cleanings while a vented spacer sheds moisture and carbon during cycling. The platform chambers 2.75-inch and 3-inch 12-gauge shells, feeds from a tubular magazine, and uses Mossberg's signature tang-mounted safety. Across its variants the 940 offers an enlarged and beveled loading port, elongated elevator, oversized bolt release, extended charging handle, and a synthetic stock with adjustable length of pull plus interchangeable drop-and-cast shims. The 940 line spans competition, tactical, field, turkey, and waterfowl configurations built on this common gas-operated action.

The Mossberg 940 was born in the competition shooting world, where Jerry Miculek -- widely regarded as the greatest speed shooter of all time -- collaborated with Mossberg to refine the gas system and controls of the 940 JM Pro. That competition-proven action became the basis for the entire 940 family, bringing 3-gun-inspired features like the enlarged loading port and extended controls to hunting, tactical, and home-defense shooters.

Mossberg 940 specifications

The 940 platform represents a significant evolution from the earlier Mossberg 930 and 935 models, replacing the pusher-rod gas system with a piston-and-sleeve design that rides over the magazine tube for cleaner, more reliable operation. It launched as the JM Pro competition model before Mossberg expanded the line into tactical, field, waterfowl, and turkey variants. Magazine capacity, barrel length, choke system, and sights vary by configuration; the field/sporting models typically use a 28-inch vent-rib barrel with Accu-Choke tubes, while the tactical model uses an 18.5-inch barrel. All 940 Pro models are manufactured in Eagle Pass, Texas.