SIG’s Rattler: SIG SAUER’s Piston-Driven PDW Extraordinaire

By Todd Burgreen | Photos by Richard King

The SIG SAUER MCX Rattler .300BLK is not just another compact AR platform. Its folding stock and diminutive size-firepower ratio are big indicators of this. The original MCX spawned from a United States Special Operations Command (SOCOM) request to develop a lightweight, compact 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 quickly following. The Rattler is a specialized miniature offshoot—pun intended—of the MCX VIRTUS series of rifles.

Precisely as you would expect from SIG SAUER’s reputation for quality, the MCX design was not hastily introduced in knee-jerk fashion. In fact, SIG SAUER spent years honing the idea before introducing the MCX. The improvements in the MCX VIRTUS are evidence of even greater refinement. It is a distinct system with features that justify this claim.

The VIRTUS improvements include a tapered lug bolt group, two-stage SIG Matchlite Duo trigger, thicker receiver/barrel (the reason that MCX and MCX VIRTUS barrels/bolt groups are not compatible), M-LOK handguard and modified gas port location. All of the improvements were driven by additional Tier One DOD unit contract requests that sought to increase accuracy, modularity and durability. The MCX Rattler originated from a similar request.

SIG SAUER has seen fit to produce not only select-fire Rattlers exclusively for law enforcement (LE) and the military, but also semi-auto SBR and pistol versions for civilian consumption. With that said, this article benefits from experience with both select-fire and semi-auto SBR Rattlers thanks to days spent at the SIG SAUER Academy.

What sets the Rattler apart, even from its VIRTUS brethren, is the compact size made possible by the 5.5-inch barrel (1:5 twist). The 23.5-inch Rattler weighs under 6 pounds and is chambered in .300BLK, with a 5.56mm version surely arriving soon too. A free-floating M-LOK handguard is paired with a Rattler-specific MCX compact upper matched with a thin folding aluminum stock. For full disclosure, the Rattler does not offer the barrel interchangeability typical of the other MCX variants. The Rattler was...

This article first appeared in Small Arms Review V22N4 (April 2018)
and was posted online on February 23, 2018


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