The Mossberg 590 Mariner is a 12-gauge pump-action shotgun with an 8+1 round capacity, 20-inch barrel, 3-inch chamber, and Silver Marinecote finish on the receiver. The stock is black. Overall length is 41 inches and weight is 7 lbs. 
 

Key Specifications 

• Brand: Mossberg 
• Model: 590 Mariner 
• Gauge: 12 GA 
• Capacity: 8+1 Rounds 
• Barrel Length: 20 inches 
• Overall Length: 41 inches 
• Weight: 7 lbs 
• Chamber Size: 3 inches 
• Sights: Bead Front 
• Finish Type: Silver Marinecote (receiver) / Black (stock) 
• Action Type: Pump Action 
   

Features 

The Marinecote finish is a nickel-based coating applied to the metal components, developed specifically to resist saltwater and humidity. It's the main reason this variant exists. If your shotgun is going near the water, in a boat locker, or in a humid climate, the standard blued 590 will rust before this one will. 
 
Capacity at 8+1 is higher than most pump shotguns in this size class. The ambidextrous top tang safety is a Mossberg standard feature and is genuinely useful for left-handed shooters. The bead front sight is basic but functional for the short-range work this shotgun is designed around. Fixed stock with pistol grip gives a conventional feel. 
 

Usage 

The 590 Mariner is designed for home defense and maritime use. Anywhere moisture is a concern. At 7 lbs. with a 20-inch barrel it's not small, but it's manageable. The 8+1 capacity is the main practical advantage over shorter-capacity alternatives.

Owners of the Mossberg 590 Mariner consistently highlight the Marinecote finish as the reason they chose this model over standard 590 variants. People who keep a shotgun near water, in humid storage, or aboard a boat mention it specifically and are satisfied with how it holds up.

Reliability is a recurring positive. The 590 platform generally has a strong track record with pump-action operation, and the Mariner variant doesn't change that. The 8+1 capacity gets favorable mention as well.

Ergonomics are described as good. The weight distribution is considered workable, and recoil is manageable for most shooters with standard loads. The ambidextrous tang safety is noted as a practical feature.

Customization comes up often, lights, slings, and aftermarket sights are common additions, and the 590 platform has plenty of options. The Marinecote finish is noted as slightly unusual in appearance compared to traditional blued finishes, which some owners appreciate and others find less appealing.

Price discussions land around whether the Marinecote premium is worth it compared to a standard 590. Most buyers who specifically need the corrosion resistance think it is; those who don't need it for wet environments question the value.