The Mossberg 590 Shockwave is a pump-action 12 gauge firearm classified as a pistol-grip firearm (not a shotgun under federal law), which means it falls outside the NFA short-barreled shotgun category while remaining subject to state and local regulations. 
 

Key Specifications 

• Brand: Mossberg 
• Model: 590 Shockwave 
• Gauge: 12 Gauge 
• Action: Pump Action 
• Capacity: 5+1 rounds 
• Barrel Length: 14.4 inches 
• Chamber Size: 3 inches 
• Weight: 6 lbs (approximately) 
• Overall Length (OAL): 26.4 inches 
• Sights: Bead front sight with rear Crimson Trace Laser Saddle 
• Stock Material: Synthetic with Raptor Birdshead Grip 
   

Detailed Features 

The Raptor Birdshead Grip keeps both hands in line during the pump stroke and reduces the leverage that creates muzzle flip. The Crimson Trace Laser Saddle mounts over the receiver and projects a visible aiming point in low-light conditions, useful when a shoulder mount is not possible. The ambidextrous tang safety operates with either hand. At 26.4 inches overall and 6 lbs, it is compact enough for vehicle storage or tight spaces.

The 590 Shockwave divides opinion almost entirely along two lines: people who trained specifically for it and people who grabbed it without adjusting technique.

Shooters who practice the push-pull hold with the Birdshead grip find it manageable and note the compact size as a genuine advantage in confined spaces. The Crimson Trace laser gets consistent praise for low-light usability. Reliability across standard loads is generally reported as good.

The criticism concentrates on recoil -- without a stock to distribute it, full-power 12 gauge loads are harder to handle than in a conventional shotgun -- and on ergonomics for people with larger hands finding the Birdshead less intuitive. Legal classification questions come up regularly in discussions, since some states treat it differently than others. Battery life and durability concerns about the laser accessory also appear in a minority of reviews.