Spain get MCX Rattler similar to the AR-15/M4 firing the .300 BLK

MADRID, SPAIN — The Spanish Civil Guard has acquired a small batch of MCX Rattler submachine guns – 15 units – from the manufacturer Sig Sauer for the body’s agents participating in missions abroad. In this way, having a military nature, the Civil Civil Guard became the first user in Spain of this submachine gun. It was purchased in mid-2022 by the United States Special Operations Command, USSOCOM.

Spain get MCX Rattler similar to the AR-15/M4 firing the .300 BLK
Photo credit: SOCOM

The Rattler is part of Sig Sauer’s MCX Virtus family of rifles that use a piston firing mechanism. This is a rifle very similar to any other rifle in the AR-15/M4 family. The lower set ─receiver box─ is made of aluminum. The rifle allows the use of standard Stanag [NATO] magazines and includes an ejection port dust collector and deflector for ejected cartridges.

Generally speaking, this is a compact rifle that allows for discreet or even concealed carry. Its weight is reduced, to only 2.59 kg, with a height of 20.3 cm, a total length of 59.7 cm, and a total width of 71 mm. The entire system is designed to work without replacing any parts. In fact, Sig Sauer guarantees that no part needs to be replaced before 20,000 shots.

The levers and buttons have exactly the same layout and operation as any AR-15 rifle, eliminating the need for additional training. On the left side of the receiver is an extended bolt catch lever, as well as the magazine catch button and safety valve. The MCX Rattler features a magazine catch and safety cap on both sides, along with an ambidextrous cocking lever.

29 Barretta rifles were also ordered

Along with this batch of Sig Sauer .300 BLK [7.62×35 mm] submachine guns, the Civil Guard has purchased five more precision rifles and 29 assault rifles from the Italian company Beretta. The contract, worth a total of 228,750 euros, was signed at the end of last year and provided for the delivery of the new weapons before December 15.

.300 BLK cartridge

The Civil Guard chose the .300 BLK cartridge for its new MCX Rattler submachine guns, developed in 2009 by Advanced Armament Corporation [AAC]. The cartridge has good short barrel firing characteristics and low noise levels with a suppressor and is compatible with the AR-15/M4 family.

AR-15/M4 compatibility allows the same magazines to be used as the cartridge dimensions are nearly identical. The 5.56mm NATO AR-15/M4 cartridge measures 57mm, the same as the .300 BLK, and the base diameter of the cartridge is 9.58mm and 9.6mm, respectively. The difference between the two cartridges is the length of the case [44.70 mm and 34.7 mm] and the diameter of the projectile [5.7 mm and 7.8 mm].


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