Benelli MR1 / Beretta RX4 Storm rifle (Italy)

 Beretta RX4 Storm rifle (pre-production version) with 10-round magazine, right side. Retractable butt extended.

 Benelli MR1 rifle (previously known as Beretta RX-4) with 30-round magazine, right side.

Benelli R1 hunting rifle, a parent design for Beretta RX4.

Type / action	gas operated, semi-automatic rifle
Caliber(s)	5,56x45mm / .223 Remington
Weight unloaded	3,18 kg / 7 lbs
Length	942 mm / 37,1"
Barrel length	406 mm / 16" (also 317 mm / 12,5")
Magazine capacity	10, 20 or 30 rounds

Beretta RX4 rifle, which was first announced in 2006, is quite unusual in that it is an adaptation of a medium-caliber hunting rifle (Benelli R1 ARGO) to smaller-caliber "home defense" weapon. The close relationships between Benelli and Beretta companies must not surprise the reader, as Beretta holding owns the Benelli company, and thus has direct access to all Benelli projects. Beretta RX4 looks like it was assembled from parts of different guns, and actually it is. The receiver and gas system are based on Benelli R1 rifles, but with alternate polymer magazine housing attached below, which will accept M16 / Ar-15 type magazines. Buttstock is apparently borrowed from Benelli's combat shotguns such as M4 Super 90. Nevertheless it appears to be a practical weapon, suitable for home defense, practical shooting, and security / police work. 
For a variety of reasons, Beretta decided to change the brand name on this design, and now it is manufactured and marketed under the "Benelli" brand, as Benelli MR1 semi-automatic-rifle.

Beretta RX4 / Benelli MR1 rifle is gas operated, semi-automatic rifle. Benelli's patented auto-regulating gas system (ARGO) consists of a gas block with dual short-stroke gas pistons, located below the barrel and concealed under the forearm. Barrel is locked by rotating bolt with three lugs. Gun is fed using any M16 / Ar-15 compatible magazines, which is a plus. Since the return spring is located in the butt, Benelli MR1 cannot be easily adapted for side-folding buttstock. As issued, Benelli MR1 rifle is equipped with adjustable open sights, and a Piactinny type rail on the top of receiver. Additional accessory rails can be installed by user on 3-, 6- and 9-o'clock positions of forearm.