The Mossberg 590A1 is a pump-action shotgun chambered in 12 Gauge with an 18.5-inch heavy walled barrel. It has a Black Parkerized finish on both the barrel and the receiver, which is drilled and tapped. The configuration includes a fixed black stock, M-Lok forend, and a cylinder bore choke. 
 

Key Specifications 

• Brand: Mossberg 
• Model: 590A1 
• Caliber: 12 Gauge 
• Action: Pump Action 
• Capacity: 6+1 
• Barrel Length: 18.5 inches 
• Color/Finish: Black Parkerized 
   

Detailed Features 

• Heavy walled 18.5-inch barrel with threaded muzzle 
• Black Parkerized finish on barrel and steel receiver 
• Drilled and tapped receiver for optic mounting 
• M-Lok forend for accessory attachment 
• Fixed black stock; cylinder bore choke included

Owners of the 590A1 consistently point to the heavy walled barrel and Parkerized finish as the main reasons they chose it over lighter-duty pump guns. The build feels dense in the hand, which splits opinion: some appreciate the solidity, others find the weight tiring over a long session.

The M-Lok forend gets a lot of attention in setup discussions. People appreciate being able to add lights or grips without adapters, though a few note the factory forend itself can feel rough until it breaks in. The fixed stock is generally liked for its no-nonsense geometry.

On value, the 590A1 sits above entry-level pumps and owners tend to think the price is justified by the receiver construction and the drilled-and-tapped top. The cylinder bore choke is a point of debate: practical for close use, but those wanting to pattern tighter loads wish it came with interchangeable chokes.