Dead Air Sierra 5 KeyMo Suppressor: Full Review

Dead Air’s Sierra 5 is a unique can. It’s compact, overbuilt, and designed to suppress everything from ARs to bolt-action .22 centerfires. To learn more about the capabilities of this versatile can, I spoke with Dead Air founders Mike Pappas and Todd Magee. 

“The impetus for the Sierra 5 was a military solicitation for an ultra-compact weapon system,” said Magee. “We designed and built the SIERRA 5 to be small, achieve the necessary decibel requirements, and emit virtually no flash signature. With the KeyMo mount installed, the SIERRA 5 is just 6.27 inches long and 1.55 inches wide, but it functions as well or better than much larger cans.” 

By using Cobalt 6 baffles and a mix of 17-4 and 316 stainless-steels for the outer tube, Dead Air’s Sierra 5 has no barrel length restrictions even on machine guns. According to Magee, how it’s built matters as much as the material selection.

“One of the main things about the Sierra 5 is how we built it,” said Magee. “It’s welded together in such a way that the back end is essentially monolithic. The 17-4 super alloy blast chamber is welded to a Cobalt 6 baffle stack, producing a straight structure with less bowing. It’s concentric and can withstand tremendous abuse.”

According to Pappas, additional objectives for the Sierra 5 was weight and modularity.  

“The goal was to make a very small and lightweight 5.56 can that was modular,” said Pappas. “It has our front cap architecture, and at the rear, it accepts our Xeno and KeyMo mount as well as a plethora of direct-thread HUB mounts on the market today.” 

From Dead Air, the Sierra 5 ships with either a KeyMo or Xeno mount. The KeyMo version shown here is an easy, user-friendly QD system. In fact, KeyMo has proven so effective that it’s become the industry standard QD mount. 

“KeyMo is just plain simple,” said Magee. “It attaches in less than one rotation and fully clamps down onto the barrel. By using a thread-to-taper system, the KeyMo bites down on the taper to resists loosening. To keep it tight, we also use a detent system to handle high vibration and the extreme thermal shifts that hard-use suppressors endure. Due to the taper, you can torque suppressors down as tight as you want, and because the suppressor can only attach one way, it’s always repeatable, enhancing precision and accuracy.”  

Another advantage of KeyMo is the aftermarket support. Flash hiders and muzzlebrakes are available from both Dead Air and many other companies. Due to its popularity and performance, KeyMo-pattern muzzle devices are used for pinning and welding to 13.9- or 14.5-inch barrels. Permanently on the barrel, the suppressor mount shaves length compared to a standard 16-inch barrel. 

“KeyMo is a brilliant mount setup and widely available,” said Pappas. “Choose from tons of mounts on the market. Forward Controls Designs, LANTAC USA, and JMAC Customs are great examples who offer solutions. KeyMo is the most supported QD system on the market.”

High performance often comes with a high price tag. Fortunately, Dead Air designed the SIERRA 5 to perform well without costing a fortune. Its MSRP is $859 (Xeno) and $929 (KeyMo). 

“The Sierra 5 will be in our lineup for a long time,” said Magee. “It’s compact, highly manufacturable, priced well, and suppresses as well as much larger cans. Could we 3D-print a smaller and lighter can with exotic metals? Sure, but it would cost a lot more. For the performance it provides, the SIERRA 5 is great value.” 

To attach the Sierra 5 to your muzzle device of choice, Dead Air added knurling to the tube. This nonslip, utilitarian approach is easy to grab with hands, gloves, or a strap wrench. It’s an old-school approach that not only works but looks cool as well. 

“The knurling isn’t just for function,” said Pappas. “It’s also a nod to the 1980s and looks awesome. People want to touch it.”

Dead Air’s Sierra 5 is a well-balanced suppressor. It’s small, affordable, cuts both noise and muzzle flash, and works with virtually any mount. It may not be the quietest or the lightest can made, but ounce-for-ounce and dollar-for-dollar, the Sierra 5 holds its own against any can out there.

Dead Air Sierra 5 KeyMo

• Type: .Rifle Suppressor
• Cartridge Rating: .22 Centerfires, 5.56 NATO
• Mount: Xeno, KeyMo, HUB 
• Overall length: 5.72 in. (Xeno adapter), 6.27 in. (KeyMo adapter)
• Weight: 13.3 oz. (Xeno adapter), 15.4 oz. (KeyMo adapter)
• Diameter: 1.55 in. 
• Materials: Cobalt 6, 316 and 17-4 stainless steel
• Finish: High-temp Cerakote, nitride adaptor and mount
• MSRP: $859 Xeno, $929 KeyMo
• Manufacturer: Dead Air; deadairsilencers.com