With the release of the MPX a few years back, SIG Sauer introduced an intriguing concept.
The submachine gun was supremely adaptable, allowing a shooter to switch calibers and configuration on the fly. Of course, for a civilian to get a hold of this technology required either deep pockets or a job in law enforcement or the military.
Those days, however, have past with the introduction of the SIG MCX at the 2015 SHOT Show. The new firearm incorporates many of design features of its select-fire cohort, in a semiautomatic package.
Of the pieces of engineering carried over to the MCX, the most intriguing is the firearm’s ability to jump between calibers. The firearm is designed to chew through three different rounds through conversions that can be made in the field, without tools.
For the MCX to go from .300 Blackout to 5.56 NATO, all that needs to be done is a barrel switch. The move to 7.62x39mm is a hair more involved, not only requiring barrels to be swapped, but the bolt as well.
While the MCX has the ability to handle multiple rounds, the European/American gun maker aimed its design to the .300 Blackout. In particular, the configuration of the firearm easily accepts the addition of a suppressor for the eminently suppressible round.
The SIG MCX’s piston-operation is also set up to help the firearm function reliably, whether suppressed or unsurpassed. The auto-regulating gas system is meant to make the switch between supersonic and subsonic loads smooth.
The malleability of the MCX isn’t strictly confined to caliber and suppression. The firearm takes a cue from the MPX in overall flexibility. From barrel length to stock style, nearly everything is interchangeable.
One of the features that helps make the MCX a gun for all situations is its recoil assembly. With the assembly housed completely in the upper receiver, the firearm does not require a buffer tube. As an added bonus, this allows the MCX to be outfitted with a folding stock.
The lower receiver, on the other hand, is much more familiar. The MCX’s controls are laid out in a classic AR-style with ambidextrous selector and mag release standard.
Other features of the SIG MCX include: KeyMod handgards, ambidextrous charging handle, cold hammer-forged barrel and compatibility with STANAG magazines.
The MCX is available in three configurations: rifle, short-barreled rifle (which requires a tax stamp) and pistol. The rifle variant comes with a 16-inch barrel, while the SBR and pistol are outfitted with 9-inch barrels. And the rifle and SBR come with the choice of four stocks: low profile side-folding skeletonized stock, telescoping stock, tubular side folding stock, or a folding telescopic stock.
Presently, the SIG MCX rifle has an MSRP of $1,866, the SBR $2,058 and pistol with side-folding SBX $2,132.
Gun Digest Book of SIG-Sauer, 2nd Edition