For a short-barreled, compact rifle compared to a full-size assault rifle, the SIG MCX “Rattler” seems to have it all that even the Special Ops wanted to commission it to serve as their newest PDW and replace its perfectly imperfect M4/M4A1.

Portability, Concealment, and Lethality

In May, the U.S. Special Operations Forces (SOF) issued a notice of intent to acquire the short-barreled rifle MCX “Rattler” series by SIG Sauer as its personal defense weapon (PWD) warranted under a five-year sole-source contract. The procurement will comprise a complete set of PDW weapons, including “suppressors (SL series), cleaning kits, magazines, quick barrel change kits, and force on force training kits.” Additional parts, sustainment, and new equipment training will also be part of the commercial PDW contract allowing the SOF to maximize its firepower in a concealable weapon.

“After years of continuous market research, USSOCOM HQ has concluded that Sig Sauer is the only vendor that can fulfill USSOCOM’s need for the Commercial PDW requirement,” the notice stated. In addition, the USSOCOM HQ has extensively researched and thoroughly reviewed different systems since 2017 to replace the M4/M4A1. Still, none of the commercial vendors’ proposed weapons passed the technical requirements—except for the SIG MCX “Rattlers.”

Accordingly, the MCX “Rattler” is said to be more reliable than the M4/M4A1. Unlike the direct impingement system the M4 depends on, the “Rattler” employs a combined gas piston system and dual recoil springs that reduces jamming issues.

Moreover, it crosses out the primary aspects SOCOM has in mind in picking a new rifle—size, portability, rapid fielding, and lethality. Not to mention its “buttstock kit solution,” another M4A1 platform problem.

The Perfect PWD Weapon For the Special Ops

Currently, the MCX “Rattler” has three versions: the MCX “Rattler” SBR that chambered the 5.56 NATO or the 300 Blackout (Blk), the MCX “Rattler” PCB, and the MCX “Rattler” Canebrake, which both can only be loaded with 300 Blk rounds. The first two platforms are purpose-built to be a discreet PDW, having only 5.5-inch in barrel length and an overall length of 23 inches. In addition, all versions have a foldable or collapsable stock that makes it easier for concealment and stowage while retaining power, reliability, and precision.

(Image source: SIG SAUER)

General Specifications of an MCX “Rattler” SBR

  • Mag type: AR-15
  • Barrel length: 5.5 in (140 mm)
  • Height: 8 in (203 mm)
  • Overall size: 23.5 in (597 mm)
  • Overall width: 2.8 in (71 mm)

As mentioned, the “Rattler” SBR can chamber the 5.56 NATO or 300 Blk, capable of loading munitions from the larger M4A1 carbine and other standard-issue infantry rifles in the U.S. inventory. Both have similar specifications, except that the 5.56 NATO version has a 1/2 in – 28 TPI thread and weighs 6 lbs (3 kg), whereas the 300 Blk version doesn’t have any thread and weighs less than 6 lbs.