A most interesting choice of weapon, especially for 1/6 scale as I had not seen this weapon before until now. Apparently, this weapon was seen in use in Tom Clancy's Ghost Recon Advanced Warfighter 2 (GRAW 2) tactical shooter video game series, published by Ubisoft.
The Beretta Rx4 is a rifle developed and manufactured by Beretta Holding of Italy. The action is a Gas-operated, rotating bolt, using the Auto-Regulated Gas-Operated system patented by Benelli. The rifle uses STANAG magazines and can feature either a fixed stock or an adjustable stock. [ source: wiki ]
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.
Beretta RX4 Storm rifle with 10-round magazine, grenade launcher and retractable butt stock
Benelli MR1 rifle (previously known as Beretta RX-4) with 30-round magazine
The Rx4 Storm is thus currently not in any military use, as it has not been intended to be, albeit one of its variants (the 12,5-inch barrel "Tactical" version with pistol grip and 5-positions telescopic stock) has been intended primarily as a "patrol carbine" for Police organizations and private security operators.