Benelli, not wanting to miss out, has entered the lucrative black rifle market with Benelli MR1 Carbine, a 5.56mm gas piston operated rifle.

Benelli MR1 Carbine

The MR1 Carbine is the civilian version of the Beretta Rx4 Storm (which never took off). Benelli, a subsidiary of Beretta, designed the ARGO gas system used by the MR1/Rx4 and manufactured both the MR1 and the Rx4 Storm.

Beretta RX4 Storm with accessories. The collapsible stock is not available currently on the RX4.

What differentiates the MR1 from other 5.56mm rifles is the gas system it uses. Originally the Auto-Regulating Gas System (ARGO) was designed for the Benelli M4 Super 90, better known by its US Military designation, the M1014 Joint Service Combat Shotgun. Benelli then adapted the system for their ARGO line of hunting rifles (branded the R1 in the United States). In 2005 the Beretta Rx4 Storm, a tactical version of the ARGO rifle, was introduced and marketed to law enforcement. As far as I know the Rx4 has never been available in a select fire variant but they decided to market it to civilians as the Benelli MR1.

Benelli M4 Super 90 / M1014

Benelli ARGO EL

The ARGO gas system has an interesting short stroke piston design. Gas is trapped very close to the chamber. The high pressure gas ensures reliable cycling regardless of ammunition. This means that it can cycle any shotgun shells, regardless of the load. For a rifle it means the barrel can be very short and a suppressor could be fitted without any cycling issues. This gun is just asking to be converted into a Short Barreled Rifle!

The gas is then fed into an expansion chamber. The pressure in the chamber drives the piston assembly, which has dual rods. The high pressure is regulated by a release value. These diagrams should illustrate how the system works.

The receiver is made of aluminum, it is fully compatible with AR-15 magazines (including the 100 round drums) and, like all Benelli shotguns and rifles, the main spring is placed inside the butt stock – meaning a folding stock is not an option, although hopefully an M1014 folding stock will be made available.

MR1 Specifications:

Caliber: 5.56mm NATO / .223 Rem.
Barrel: 16″. Hard chrome lined. 1:9 twist.
Rear Sights: Military-style Aperture
Weight: 7.9 lbs.

The MSRP is $1299. I think they have priced it right. Although not cheap, and they can do better than the one five round magazine they ship with it, I doubt they could sell it much cheaper.

MR1 with 5 round magazine.