Mossberg 590A1 12 Gauge 20in Pump-Action Shotgun

About this product

What is the Mossberg 590A1 12 Gauge 20in Pump-Action Shotgun? The Mossberg 590A1 is a heavy-duty 12-gauge pump-action shotgun built to military specifications with a 20-inch barrel and robust construction that prioritizes reliability over refinement. This is not a sporting clay gun or a lightweight hunting piece—it’s a purpose-built tool designed for high-stress environments where failure isn’t an option. The Tungsten Cerakote finish and ghost-ring sight system reflect its serious intent from the muzzle to the stock.

What is the Mossberg 590A1 used for?

The Mossberg 590A1 is used for defensive, tactical, and law enforcement applications where extreme durability and immediate reliability are non-negotiable. This shotgun is built to MIL-S-3443G standards, meaning it’s designed to endure harsh conditions, including salt spray testing and a 3,000-round reliability trial. The 20-inch heavy-walled barrel and cylinder bore choke make it effective with both slugs and buckshot inside 50 yards.

How does the Mossberg 590A1 compare to the Stevens 555 Sporting O/U 12 Gauge?

The Mossberg 590A1 is more durable and simpler than the Stevens 555 Sporting Over/Under, which is better suited for recreational clay shooting and hunting. Where the Stevens 555 uses walnut and polished blue steel for aesthetics, the 590A1 uses synthetic stocks, a parkerized metal undercoating, and Cerakote for corrosion resistance. The 590A1 is heavier at 7.25 lbs compared to the Stevens’ 7.0 lbs, but it’s built to withstand abuse the Stevens isn’t designed for.

What does it weigh and what are the dimensions?

The Mossberg 590A1 weighs 7.25 lbs unloaded and measures 40.5 inches in overall length with its 20-inch barrel. The stock includes three 0.5-inch spacers for length-of-pull adjustment between 13.5 and 14.5 inches, accommodating most shooters from 5'8" to over 6'2". The magazine tube holds 8 rounds of 2.75-inch shells or 7 rounds of 3-inch magnums.

Who is this NOT for?

This shotgun is not for hunters looking for a lightweight field gun or clay shooters wanting a fast-swinging, balanced Over/Under. At 7.25 lbs, it’s nearly a pound heavier than most field pumps and significantly heavier than something like the Stevens 555 Sporting Compact 20ga. The ghost ring sights are optimized for defensive use, not flying targets.

What’s in the box?

Included with the Mossberg 590A1 are the shotgun itself, one cylinder bore choke tube pre-installed, a choke tube wrench, and a standard 0.5-inch stock spacer (two additional spacers can be added for further adjustment). Mossberg does not include a case or cleaning kit—this is a barebones, professional-grade tool. Expect documentation and a warranty card, but no extras.

Is the Mossberg 590A1 worth it at $857.98?

At $857.98, the Mossberg 590A1 is fairly priced for a mil-spec shotgun with Cerakote finish and ghost ring sights, coming in about $150 less than a comparable Benelli M4. You’re paying for durability and proven performance, not fancy features. If you need a shotgun that will work under stress and last decades, this is a solid investment. If you’re just plinking or hunting occasionally, consider a Stevens 334 in .308 for half the price.