The Mossberg 590 SPX is a 12-gauge pump-action shotgun with an 18.5-inch barrel, 6+1 capacity, 3-inch chamber, and matte black/blued finish. It weighs 7 lbs. The FLEX stock system adjusts length-of-pull across six positions from approximately 10.75 to 14.25 inches. Ghost ring sights are included for quick target acquisition. The synthetic stock is cylinder bore. 
 

Key Specifications: 

• Brand: Mossberg 
• Model: 590 SPX 
• Gauge: 12 GA 
• Action Type: Pump Action 
• Capacity: 6+1 Rounds 
• Barrel Length: 18.5 inches 
• Weight: 7 lbs. 
• Chamber Size: 3 inches 
• Finish: Matte Black / Blued 
   

Detailed Features: 

• FLEX Stock System: Six length-of-pull positions from roughly 10.75 to 14.25 inches to accommodate different shooter sizes without tools. 
   
• Ghost Ring Sights: Ghost ring rear and blade front allow fast target acquisition compared to bead-only configurations. 
   
• Synthetic Stock: Lightweight and weather-resistant, does not warp or swell. 
   
• Cylinder Bore: No choke constriction, which works well with buckshot and slug loads at close range.

Owners of the Mossberg 590 SPX discuss it primarily in the context of reliability and home defense use. The pump-action cycles consistently across different shell types and brands, and most owners report very few issues even with budget ammunition.

Ergonomics are well-received. The adjustable FLEX stock and comfortable grip make it accessible to different body sizes, and the ghost ring sights are cited as genuinely useful for quicker target acquisition than a standard bead.

The Picatinny rail for mounting optics or accessories gets positive mentions from owners who want to add a light or red dot, which adds functional flexibility.

Capacity is viewed as a practical positive for defensive use.

At 7 lbs the shotgun is on the heavier side, which comes up in discussions about extended use or competition stages where carrying the gun for longer periods matters. Price is occasionally noted as higher than comparable 12-gauge pump options, though most buyers feel the feature set justifies the cost.

Customization options specific to this model are viewed as somewhat limited compared to other platforms, and a short break-in period is mentioned by a handful of new owners before the action smoothed out.