Breaking Away from the Norm: The Modular/Adaptable SIG SAUER MCX

By Todd Burgreen

SIG SAUER, Inc. has evolved into a recognized industry leader in the development and manufacturing of rifles, SMGs, handguns, optics, ammunition, suppressors etc. SIG SAUER has entered the rifle market in force over the last several years. SIG SAUER definitely now has “skin” in the rifle game, with numerous models and calibers in its product line-up.

Of late, the most attention seems to have been paid to “improving” the AR platform, either via developing piston-driven ARs or caliber expansion beyond 5.56mm. This leads us to SIG SAUER’s latest rifle offering, which embodies both: the MCX. The MCX represents the latest approach to rifle methodology in terms of modularity without sacrificing rugged reliability. While sharing similar aesthetics to the venerable AR, the MCX is a new approach blending adaptability of caliber and configuration.

The MCX spawned from a SOCOM request to develop a lightweight, compact multi-caliber rifle that was intended to be operated suppressed. Based on this, it is not surprising that the MCX’s initial chambering was the .300BLK, with the 5.56mm (both evaluated herein) and 7.62x39mm quickly following. Typical of the Swiss/German engineering background of the company, the MCX design was not hastily introduced in a knee-jerk fashion. The process took over three years before SIG SAUER was ready to introduce MCX to the market by designing a self-regulating short-stroke piston.

The SIG SAUER designers needed to meet a 50,000-round count criterion to satisfy the initial solicitation that brought the MCX to life. This should allay any concerns over its modularity affecting durability in terms of wear and “loosening” up with use. Obviously, quality materials are a must, along with a full understanding of high-wear parts on the rifle. SIG has designed the MCX with certain key wear components upgraded to steel versus aluminum; these parts are also easily replaceable. For example, the cam path insert and feed ramp insert. The charging handle latches move over steel pins as opposed to aluminum pins. Barrels for the SIG SAUER MCX are hammer forged and receive a nitride treatment for increased barrel life. The...

This article first appeared in Small Arms Review V21N7 (September 2017)
and was posted online on July 21, 2017


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