Sig Sauer has been busy reinventing what we expect from pistols (with the P320) and submachine guns (MPX), and now the company has introduced the new MCX, which borrows features from the proven AR-15 platform and combines it with new and existing Sig Sauer technology, bringing us a weapon that was designed from the outset as a piston-driven carbine that can fire multiple calibers with utter reliability—with or without a suppressor and as a semi-auto or select-fire weapon.

The central theme with the rifle is modularity. Users can quickly install different handguards, barrels and calibers (5.56mm NATO, 7.62x39mm or 300 Blackout), and stock configurations to suit their needs.

The upper is also designed to work with all mil-spec AR lower receivers. Anticipating the rigors that the MCX will go through, designers at Sig equipped it with wear-replaceable hard parts like the bolt cam path insert, feed ramp insert and charging handle latch points.

The MCX’s gas-operated, short-stoke piston system works well and is lightweight. Since the controls are the same as any AR’s, adaptability is not an issue, nor is operational training.

Sig has also been busy upping its game in the suppressor world, and it’s added several new models to its lineup. I recently tested one of its new SRD suppressors with the MCX while running Sig’s own Elite Performance 220-grain subsonic 300 BLK ammunition.

Check out the video and keep your eyes peeled for a full review in an upcoming issue of TACTICAL WEAPONS. To subscribe, visit

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