The Benelli M4 is a semi-automatic 12-gauge shotgun with an 18.5-inch barrel and the U.S.M.C.-approved A.R.G.O. (Auto-Regulating Gas-Operated) piston system. 
 

Key Specifications 

• Model: M4 
• Caliber: 12 Gauge 
• Action Type: Semi-Auto 
• Barrel Length: 18.5 inches 
• Overall Length: 40 inches 
• Weight: 8.4 lbs 
• Magazine Capacity: 7+1 rounds 
• Chokes: Modified (M) 
• Sights: Ghost-Ring rear with post front 
   

Detailed Features 

 
The A.R.G.O. piston system self-regulates to cycle a wide range of 12-gauge loads without requiring adjustment. Ghost-ring rear sight with a post front lets you acquire targets quickly. The receiver is drilled, tapped, and fitted with a Picatinny rail for optics or accessories. A bolt-lock lever handles safe storage or transport. The rotating bolt head locks up during firing. The trigger assembly is removable for cleaning. The telescoping stock adjusts length of pull.

The M4 Tactical with the A.R.G.O. system draws strong marks for reliability across varied ammunition types and conditions. The self-regulating gas system is the feature users discuss most, particularly in high-stress or tactical contexts where ammunition selection may not be controlled.

Build quality and materials are consistently praised. The semi-auto operation and rapid follow-up shot capability are well regarded, and the shotgun's reputation in law enforcement and military contexts carries weight in civilian owner discussions. Weight is a recurring note: 8.4 lbs is substantial and some users report fatigue with extended carry. Customization options are viewed positively. Price is the most common objection, with the M4 sitting toward the top of the market for shotguns.