The Mossberg 590A1 SPX is a pump-action shotgun chambered in 12 gauge with a 20-inch heavy-walled barrel, 3-inch chamber, and 8+1 capacity. Overall length is 41 inches, weight is 7.25 lbs (116 oz). The finish is black Parkerized; the stock is black synthetic. This is the MIL-SPEC heavy barrel variant of the 590 line, built to tighter tolerances than the standard 590. 
 

Key Specifications 

• Model: 590A1 SPX 
• Caliber: 12 GA 
• Barrel Length: 20 inches 
• Overall Length: 41 inches 
• Weight: 7.25 lbs (116 oz) 
• Capacity: 8+1 rounds (3" chamber) 
• Action Type: Pump Action 
• Finish: Black Parkerized 
• Stock Material: Synthetic (Black) 
   

Features 

The heavy-walled barrel is the defining spec of the 590A1 -- it is thicker than the standard 590 barrel and withstands the bayonet lug mount. Ghost ring rear sight and protected blade front sight give faster target acquisition than bead sights in low-light or high-stress conditions. The top tang safety is operated with the thumb without shifting grip. The synthetic stock handles weather without warping or swelling. 
 

Usage 

A capable home defense and tactical shotgun. Eight rounds in the magazine plus one in the chamber reduces the need for reloads in most scenarios. The 20-inch barrel keeps overall length manageable indoors. Parkerized finish holds up to field use better than blued steel.

The 590A1 SPX gets consistent positive feedback on reliability. The pump action is described as smooth and dependable across various ammunition types, and the 8+1 capacity is frequently cited as a real advantage. Users appreciate its versatility for home defense and range use.

Ergonomics are generally rated well, with the handling and maneuverability in tight spaces noted positively. Customization potential through aftermarket accessories draws interest from enthusiasts who want to configure the gun to their needs.

On the critical side, weight comes up -- at 7.25 lbs it is heavier than some alternatives, which can be a factor in extended handling or carry scenarios. Recoil from a 12 gauge is inherent to the caliber and gets mentioned by newer or recoil-sensitive shooters. Finish wear over time is an occasional complaint, though the Parkerized coating is specifically noted as functional rather than cosmetic. Price is viewed as fair by most, though some compare it to alternatives at lower cost.

Overall feedback is positive, with reliability and capacity being the most commonly praised attributes.