Silencer Review: Dead Air Sierra-5 5.56 NATO Suppressor

Dead Air’s new Sierra-5 silencer is a compact, heavy-duty suppressor designed for hard use on .223/5.56 firearms. Available from Silencer Shop with either a KeyMo mount system or a Xeno mount system, I got my hands on one of each and ran them through their paces over the last couple months.

With a pinned and welded KeyMo flash hider already installed on the muzzle of my Radian Weapons Model 1, it was the perfect host to test out a Sierra-5.

I visited The Range at Austin to do some initial testing with the new Atibal HYBRID12 1-12x scope and the Black Collar Arms forged carbon fiber cantilever scope mount, and put a bunch of rounds through the Sierra-5 at the same time.

While ear pro is necessary at the indoor range whether suppressed or not, I was still able to recognize the nice tone and solid suppression of the Sierra-5 along with the complete and total lack of concussion normally associated with firing 5.56 indoors.

As you can see in the photo above, the nice little Dead Air silencer maintained the excellent accuracy of this rifle. Despite popular myth it’s rare that a silencer degrades accuracy and, actually, more common that they improve accuracy. The Sierra-5 wasn’t an outlier.

Both of Dead Air’s mounting systems also provide a fully repeatable return to zero should you remove and re-install the suppressor. Any shift to your point of impact with and without a suppressor can vary wildly depending on the host firearm, but as long as any shift is perfectly consistent you won’t encounter issues. The Sierra-5 is consistent.

At least that’s the case with Dead Air’s mounting systems (Xeno seen above). A great feature of the Sierra-5 is that it’s threaded at its base with the now near-universal “HUB” mount aka 1.375×24 aka 1-3/8×24 thread size. There are many dozens of mounting systems available for this thread pitch, from QD to direct thread to pistol boosters and so much more.

Frankly, I wouldn’t complain if Dead Air also sold the Sierra-5 completely sans mount. Or maybe with just a 1/2×28 fixed mount. Though I’m a perfectly decent fan of both their KeyMo and Xeno systems, I’d rather not be forced to pay for one of these systems if I’ve already standardized my gun collection on something else.

If you’ve really standardized, there’s a pre-drilled hole at the base of the Sierra-5 that can be used to pin and weld a mount to the silencer. Presumably most people doing this would also be pinning and welding said mount to their firearm in order to use the Sierra-5 as legal barrel length (e.g. my Radian seen in this review has its KeyMo flash hider welded to its 14.5-inch barrel to meet the 16-inch legal length).

There’s space inside the base of the Sierra-5 for lots of different muzzle brakes, compensators, and flash hiders. The suppressor’s blast baffle is nice and beefy with interesting ribs down the sides that I don’t think I’ve seen before.

With Stellite baffles fully welded in a 17-4 PH stainless steel body, the Dead Air Sierra-5 is full-auto rated with no barrel length restrictions. And, yes, I fired a few mags of full-auto .223 through a 14.5-inch upper on the Xeno Sierra-5 and it shrugged it off like a champ.

Worth noting, the Xeno mount also didn’t seize up. Once the suppressor stopped smoking and cooled down I was able to unscrew it — righty loosey! — from the flash hider without issue. It’s clear that the taper section in front of the threads sealed up flawlessly and kept the threads perfectly clean.

At the same time, over the course of three or four full heat cycles across as many range sessions and one hunting trip, the Sierra-5 never came loose on me.

Last weekend both the machine gun and the Radian Model 1 accompanied a few friends and me out to Lonesome Boar Adventures in Mountain Home, Texas for some hunting. My buddy Peter chose to run the Radian most of the trip and he took a nice hog from about 140 yards.

Out on the hunt, in a deer blind, and behind the ranch house, the Sierra-5 sounded great. For a compact suppressor it performs extremely well and it has a solid, pleasing tone to it with no high-pitched pinging like many 5.56 suppressors have. If it weren’t for the supersonic crack of the projectile, the sound would be all low and dull and about as good as it gets.

Front caps are compatible with all of Dead Air’s R-Series caps including their E-Brake.

The flash hider front cap included with every Sierra-5 proved itself highly effective. In some slow-mo video I took at The Range Austin as well as out at Lonesome Boar Adventures shooting in near-dark conditions, no flash was visible.

Apparently the Sierra-5’s knurling is a topic of some debate, but I love it. I think it looks great, plus it stays looking great — much better than smooth Cerakote, which always looks dirty, scuffed, greasy, and uneven once you start using a silencer decently hard — and it provides truly fantastic grip on the silencer for removing and installing. Dead Air also says that the increased surface area improves and speeds up heat dissipation compared to their tests of the same silencer but without the knurling.

One more benefit to the knurled texture: it better secures suppressor heat covers. As someone who has experienced a suppressor wrap walking off the front of a silencer quite a few times, this is a welcome touch.

A couple months and a couple hundred rounds later and I’m a big fan of the Dead Air Sierra-5. It’s everything you want in a hard-use, minimalistic AR-15 silencer and nothing you don’t.

The Sierra-5 is compact, yet big enough to be quiet. It has no rate of fire or barrel length restrictions. It has the universal HUB (1.375×24) mount size. It’s quite modest in how it increases backpressure on a gun like my Radian, which does not have an adjustable gas system. The Sierra-5 also looks good and feels good in the hand. Plus it’s backed by a solid warranty.

If you’re looking for a dedicated .223/5.56/AR-15 silencer, the Dead Air Sierra-5 is a rock solid choice.

Specifications: Dead Air Sierra-5 (KeyMo and Xeno)

CALIBER RATING: 5.56 NATO, 224 Valkyrie
ENERGY RATING: 2200+ ft lbs
BORE DIAMETER: 5.56mm
LENGTH (NO ADAPTER): 4.87 inches
LENGTH (W/KEYMO): 6.27 inches
LENGTH (W/XENO): 5.72 inches
DIAMETER: 1.5 inches
WEIGHT (NO ADAPTER): 10.8 ounces
WEIGHT (W/KEYMO): 15.4 ounces
WEIGHT (W/XENO): 13.3 ounces
MATERIALS: Stellite® baffles, stainless steel
FINISH: Black Cerakote®
USAGE: Ideal for heavy firing schedules
BARREL RESTRICTIONS: None
FULL AUTO RATED: Yes
MSRP (KEYMO): $929 (much less via Silencer Shop)
MSRP (XENO): $859 (much less via Silencer Shop)

Ratings (out of 5 stars):

Overall  * * * * 1/2
I have no complaints. This is an absolutely fantastic AR-15 suppressor. While I’m sure there’s a reason this isn’t the case, I’m going to go ahead and say anyway that I’d have given it 5 stars if it were tubeless. I.E. if the Stellite baffles were welded together and became their own tube, rather than doing a baffle stack with a tube over the top. It would, in theory, be lighter as well as quieter (more internal air volume). Yeah, I’m grasping at straws to come up with some way it could be improved for that perfect rating.