Benelli MR1 Carbine (Civilian Beretta Rx4 Storm)

Steve Johnson
by Steve Johnson

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.
Steve Johnson
Steve Johnson

I founded TFB in 2007 and over 10 years worked tirelessly, with the help of my team, to build it up into the largest gun blog online. I retired as Editor in Chief in 2017. During my decade at TFB I was fortunate to work with the most amazing talented writers and genuinely good people!

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  • Benelli Big Bad Gun Benelli Big Bad Gun on Jun 04, 2013

    I bought one of these rifles but it did not come with an instruction manual. Called Benelli and they said they would send me one. I never received it and no follow up from Benelli. I fired my rifle and it would jam constantly with different ammo and magazines. I sent it back to Benelli for service and they sent it back to me and said nothing was wrong with it but it kept jamming and misfeeding on almost every round. I sent it back again with an even longer description of the problems with sample fired cases. They sent it back to me and said that they had to replace the entire barrel so I'm guessing there was something wrong with it all along. I took it out to test fire and it performed better. It only jammed or misfed rounds every seventh or so rounds. With the cost of ammo being what it is now, I can't really test fire it anymore. Hoping that when I can shoot again that it will function properly. I still think Benelli service is terrible considering this rifle cost me a bundle of money! I also think it's quite cheap of Benelli to supply only one magazine with this rifle. Additional five round magazines cost $85?

    • See 1 previous
    • Frank Frank on Sep 12, 2014

      @Charlie Try one type off ammo, then clean entire riffle. Then next type off ammo. My Mr1 do not like some ammo.

  • Greg Greg on Sep 12, 2014

    My Argo do not like 5.56 NATO, but never any problems with 223rem. Any other with the same issues?

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