IS SIG MCX “Rattler” A Worthy Replacement For M4/M4A1?

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.

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.

MCX “Rattler” Shooting Test

TFBTV’s James Reeves reviewed the SIG MCX “Rattler” in 2018 when the USSOCOM HQ first announced that it had purchased the compact rifle for evaluation, and these were his conclusions.

The MCX “Rattler” is the third generation of combat carbines or rifles, an actual 21st-century design. The gun has a lot of similarities with the AR-15, from the magazine release and bolt release, and consequently, can combine both with the “Rattler” on the upper and an AR-15 on the lower, with the help of the appropriate conversion kit. It also has a very similar safety; it’s ambidextrous, not to mention the grips have a similar feel and design as the AR-15s.

Moving to its firing power, Reeves said that the “Rattler” has an excellent accuracy even at 100 yards, “just standing up with no magnification … [using] Bushnell TRS 25 sight.”

“It’s really incredible for being small as it is and shooting something closer to a 7.62x39mm,” he said, adding that it has a “lighter recoiling but it’s just as powerful and probably more accurate.”

What’s more remarkable about the “Rattler” is that it has a similar exact manual of arms as the AR-15, so anybody who knows how to use the latter can pick up the SIG MCX and go.

You can check out more details of the review and shooting test below.

But how much is it? Well, a unit of SBR costs around $2,727, while the PCB costs approximately $2,299. However, how much the government will be spending on the procurement is undetermined, as they didn’t disclose yet how many rifles will be procured or at what value each firearm will be. MCX “Rattler,” nonetheless, holds promising features that provide the SOF the much-needed advantages that certainly make it worth the money.

But what do you think? Will the SIG MCX Rattlers become a helpful asset and a worthy successor to the M4/M4A1? Let us know in the comments below!