The Mossberg 590M Shockwave Breacher is a 12-gauge pump-action shotgun with a 14.38-inch barrel and a detachable box magazine holding 10 rounds. It has a 2.75-inch chamber, M-Lok forend, and a birdshead grip. The receiver is drilled and tapped with a matte blued finish. The barrel is heavy-walled and threaded with a breacher muzzle device. 
 

Key Specifications 

• Brand: Mossberg 
• Model: 590M Shockwave 
• Caliber: 12 Gauge 
• Action: Pump Action 
• Capacity: 10 rounds 
• Barrel Length: 14 inches 
• Finish: Matte Blued 
   

Detailed Features 

• 14.38-inch heavy-walled barrel with 2.75-inch chamber 
• Detachable box magazine with 10-round capacity 
• M-Lok forend for accessory attachment 
• Breacher muzzle device 
• Birdshead grip configuration 
• Drilled and tapped receiver

The Mossberg 590M Shockwave Breacher draws a specific crowd: people who want compact 12-gauge capability in a non-NFA configuration. The birdshead grip and short barrel make it easy to maneuver, and the 10-round detachable magazine is the headline feature that sets the 590M apart from tube-fed Shockwaves.

The M-Lok forend and drilled-and-tapped receiver give owners a clear path to add lights or sights, which is a common upgrade. The heavy-walled barrel with breacher muzzle also sees praise from those who want a purpose-built entry option. Recoil management with the birdshead grip takes practice and splits opinions among new owners.

The 590M is not a range toy for most buyers and that shapes how it is reviewed. Those who use it as intended tend to be satisfied; those who expected a comfortable high-volume shooter come away less enthusiastic.