Upgraded Assault Rifles In Store for Commandos

By Scott R. Gourley

Sig Sauer photo

U.S. Special Operations Command is already looking to expand the capabilities of its Reduced Signature Assault Rifle — formerly known as the Personal Defense Weapon — before its manufacturer has even delivered the first weapon in the program.

The command is considering the addition of conversion kit options to incorporate 7.62x39 mm caliber ammunition, which is most used in the AK-47 series assault rifle, a “notice of intent” released late January stated.

The original program emerged in March 2017, when the command released an announcement seeking to identify “potential sources within the national technology and industrial base with the ability to provide a conversion kit for the 5.56 mm M4A1 to create a Personal Defense Weapon system.”

Kit requirements included conversion to fire the .300 Blackout cartridge, a system weight not to exceed 5.5 pounds, extended length not to extend 26 inches and length with stock collapsed or folded to be 17 inches, with the weapon fully functional when collapsed or folded. The kits also needed to include a 5.56 mm barrel that allowed the weapon to be changed from .300 Blackout to 5.56 mm in less than three minutes.

The .300 Blackout provides several tactical differences when compared to the 5.56 mm. First, while most 5.56 mm operational projectiles fall within the general range of 55 to 77 grains, the .300 projectile falls within the general range of 110 to 120 grains. At a comparable velocity, that translates to more energy on target.

Additionally, on the subsonic side, the .300 Blackout provides a fully suppressible cartridge that is not available in 5.56 mm. Many gun and ammunition manufacturers believe that the combination of increased performance in the supersonic range and subsonic capabilities combined to “popularize” the .300 Blackout for many special operators, with potential benefits from the 5.56 mm conversion kit ranging from the availability of training ammunition to addressing possible “shoot house” restrictions.

Meanwhile, Special Operations Command elements continued to explore optimized barrel lengths and barrel twist rates for the .300 Blackout in a potential short-barrel carbine configuration.

Sig Sauer responded to the 2017 Personal Defense Weapon program with a version of its MCX “Rattler.” The command subsequently acquired approximately 340 of the guns with 5.5-inch barrels in .300 Blackout, with the ability to convert the guns back to 5.56 mm, according to Jason St. John, senior director of government products at Sig Sauer.

In May 2022, Special Operations Command announced its intent to award the Personal Defense Weapon contract to Sig Sauer, acknowledging in a statement that “after years of continuous market research,” headquarters had concluded that Sig Sauer was the only vendor that could fulfill the need for the commercial Personal Defense Weapon requirement.

“We have meticulously reviewed each system for technical acceptance and whether it fits the commercial definition. Except for Sig Sauer, the vendors did not meet the technical requirements and/or the weapons do not meet the commercial definition,” it said.

The contract award in late September identified the program’s new name — the Reduced Signature Assault Rifle. It cited a five-year indefinite delivery/indefinite quantity contract to provide a complete weapon system — Sig Sauer Rattlers in 5.56 mm and .300 Blackout caliber — that includes suppressors, cleaning kits, magazines, quick barrel change kits, force on force training kits and other accessories.

Approximately 800 guns will be acquired under the Reduced Signature Assault Rifle program, which features a slightly enhanced version of the Rattler platform in .300 Blackout — convertible to 5.56 mm — with a seven-and-three-quarters-inch barrel.

St. John noted that the company had not started deliveries as of late February but anticipated that the order would be completed “this year.”

But before deliveries even began, the January notice of intent cited “developing requirements” that called for “7.62x39 mm upper receiver caliber conversion kits that are compatible with the Sig Sauer Rattler lower receiver.”

“That's the beauty of the MCX design,” St. John said. “The MCX has a self-contained barrel clamp and the ability to rapidly change calibers through our ‘CAL-X’ exchange kits for MCX platform.”

The modularity of the Rattler in general has everything from the six-and-three-quarter-inch .300 Blackout barrel through nine-, 11-, 14- and 16-inch options, he said. And there are variations throughout different calibers, he noted. And the modular design allows Special Operations Command to buy just one firearm in .300 Blackout and then just a 7.62x39 mm kit to convert it, he noted.

In addition to the 7.62x39 mm seven-and-three-quarter-inch barrel and new bolt, the conversion will also require an AK-style “curved magazine” to address the taper of that round, he said.

Topics: Guns, Special Operations, Ammunition

Comments (1)

Re: Upgraded Assault Rifles In Store for Commandos

Surprised they didn't rechamber it for the new 6.8mm rounds.

Johnathan Galt at 5:12 PM
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