Mossberg 590A1
O.F. Mossberg & Sons · Shotgun · In Production · 1987
Also known as: M590A1, Mossberg 590A1 Tactical, Mossberg 590A1 MIL-SPEC
Overview
The Mossberg 590A1 is a heavy-duty, military-specification pump-action combat shotgun manufactured by O.F. Mossberg & Sons. Developed as a purpose-built military variant of the Mossberg 590, the 590A1 is the only pump-action shotgun to have passed the United States Army's demanding MIL-SPEC 3443E endurance and environmental testing protocol, which subjects the weapon to over 3,000 rounds of full-power 12-gauge buckshot along with extensive drop, impact, and environmental abuse tests. The 590A1 was created after the U.S. military identified specific deficiencies in the standard Mossberg 500 platform during evaluation in the late 1970s. Key upgrades over the base 590 include a heavy-walled barrel (originally requested by the U.S. Navy so the weapon could withstand being slammed in the steel doors of frigates without barrel deformation), a metal trigger guard and metal safety button replacing the standard polymer components (required to meet MIL-SPEC 3443G material specifications), and a clean-out magazine tube that allows rapid clearing without full disassembly. The 590A1 features the Mossberg family's signature ambidextrous top-mounted tang safety, dual action bars for smooth and reliable cycling, an anti-jam elevator, steel-to-steel lockup, and dual extractors. Available with 14-inch (NFA/Class III), 18.5-inch, and 20-inch heavy-walled barrels in 6+1, 7+1, and 9+1 capacities, the standard military configuration features a 20-inch barrel with 8+1 capacity, bayonet lug, ghost ring sights, Parkerized finish, and synthetic stock. The 590A1 has been in continuous U.S. military service since 1987 and has been adopted by armed forces and law enforcement agencies worldwide, seeing extensive combat use in Iraq, Afghanistan, and numerous other theaters of operation.
Specifications
| Weight (empty) | 3290 g (116.1 oz) |
| Overall Length | 1041 mm (40.98") |
| Barrel Length | 508 mm (20.00") |
| Action Type | Pump Action |
| Firing Mechanism | Hammer Fired |
| Trigger Type | Single Stage |
| Trigger Pull | 38 N (8.5 lbf) |
| Magazine Capacity | 8 rounds |
| Magazine Type | Tubular |
| Muzzle Velocity | 457 m/s (1499 fps) |
| Effective Range | 40 m (44 yd) |
| Barrel Rifling | Smoothbore |
| Number of Grooves | 6 |
| Frame Material | Aluminum |
| Barrel Material | Steel |
| Stock Material | Synthetic |
| Finish | Parkerized |
Calibers
- 12 Gauge · primary — also known as 12 ga, 12 bore
Features
- Firing modes: Manual
- Feed systems: Tubular Magazine
- Safety mechanisms: Tang Safety, Trigger Disconnect
- Features: Heavy Walled Barrel, Metal Trigger Guard, Metal Safety Button, Dual Action Bars, Anti Jam Elevator, Clean Out Magazine Tube, Bayonet Lug, Ghost Ring Sights, Drilled And Tapped Receiver, Steel To Steel Lockup, Dual Extractors, 3 Inch Chamber, Cylinder Bore, Mil Spec 3443 Construction
Variants
- Mossberg 590A1 Compact — Compact
- Mossberg 590A1 SPX — Tactical
- Mossberg 590A1 Retrograde — Classic
- Mossberg 590A1 Magpul — Accessorized
- Mossberg 590A1 Class III (14-inch SBS) — Short Barrel
- Mossberg 590A1 M-LOK — Accessorized
Base model
Service history
Operators
- United States Army · adopted 1987 · as M590A1
- United States Marine Corps · adopted 1987 · as M590A1
- United States Navy · as M590A1
- United States Coast Guard · as M590A1
- United States Air Force · as M590A1
- French Armed Forces
- Iraqi Armed Forces
- Israel Defense Forces
- Royal Netherlands Armed Forces
- Portuguese Armed Forces
- Republic of Korea Armed Forces
- United States Law Enforcement (multiple agencies) · as 590A1
Conflicts
- Gulf War (1990-1991)
- Somali Civil War (1992-1995)
- War in Afghanistan (2001-2021)
- Iraq War (2003-2011)
Production
Production years: 1987-present
Production numbers not publicly disclosed. All branches of the U.S. military and Coast Guard have ordered 590A1 shotguns. New $11.6 million U.S. Army contract awarded in 2025. Adopted by military and law enforcement in over 70 countries.
Origin
Country of origin: United States
Designer: Carl Benson
Notes
The 590A1 was the U.S. military's primary combat shotgun from 1987 until the semi-automatic Benelli M4 (M1014 JSCS) began supplementing it in the early 2000s. However, the 590A1 remains in active U.S. military service alongside the M1014, with a new $11.6 million U.S. Army contract awarded to Mossberg in 2025 for additional 590A1 units. The updated MIL-SPEC 3443G specification now requires a metal trigger guard, meaning only 590A1 variants (not standard 500 or 590 models) can meet current military requirements. The 590A1 Class III variant with a 14-inch barrel is restricted to military and law enforcement sales as a short-barreled shotgun under U.S. federal law. The SPX variant adds a Picatinny rail, LPA adjustable ghost ring sight, and M-LOK forend. The Retrograde variant features a walnut stock and forend with a heat shield, recalling the aesthetic of classic military combat shotguns. All 590A1 models use Mossberg's cylinder bore choke, optimized for buckshot and slug patterns at combat distances. The heavy-walled barrel, while slightly increasing weight over the standard 590, provides significantly improved durability and heat dissipation during sustained firing.
Background
The Mossberg 590A1 is the only pump-action shotgun to have passed the U.S. Army's MIL-SPEC 3443E torture test -- a brutal protocol involving 3,000 rounds of full-power buckshot, repeated drops onto concrete, and extreme environmental exposure. The heavy barrel was born from a U.S. Navy requirement: sailors needed a shotgun barrel tough enough to survive being caught in the slamming steel doors of warships without bending.