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Launched this spring at the NRA Show, 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
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
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.


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  1. “Got your hands on”
    Did you purchase?

    If so, how long was the wait for Eform4 approval?

    I’m currently over 170 days.

      • Yes. I submitted everything via the Silencer Shop kiosk at my local FFL. Was done as a ‘One Shot’ Trust.

        I’ve talked with three NFA point people at local FFL that handle NFA items. Was told by all three they haven’t seen a single Eform4 approval dates later then February of this year. That’s seven months.

      • This is incorrect. The ones that we are seeing come back are running around 6 months right now. They haven’t been reliably 90 days since around the very beginning. James, I would bet yours comes back very soon.

        • Silencer Shops website backs up what I’ve established in the past week……

          eForm 4 – TRUST: 1 Day through 7 Months 6 Months
          eForm 4 – INDIVIDUAL: 6 Months through 7 Months 6 Months…..

          SS updated that info around two weeks ago.

          I’m hoping to see my tax stamp soon.

          There’s a glitch in the matrix. 🤔

        • Weird!!! I saw they were meeting their 90 day approval goal very reliably for the first couple months and didn’t realize that had changed 🤦‍♂️. Sorry. I guess be patient as usual with this crap then haha

          I’m on Silencer Shop’s SOT so I can borrow silencers from them for the purpose of testing and reviewing them. They have demo cans for nearly everything they carry. I also have my own SOT so sometimes get my hands on and review ones that Silencer Shop doesn’t carry.

        • I’m surprised suppressor manufacturers and retailers aren’t contacting their state reps in DC about the obsurd wait times.

          During the last ATF/NFA funding increase, the DOJ and State Reps gave a directive to the ATF that Eform4s waits be reduced to 90 days by the end of 2022. ATF ASSURED the DOJ and State reps that sufficient staff would be assigned to the E-Form system to accomplish that directive.
          By all measures ATF/NFA has failed to meet that agreed upon goal while getting those increased funds.

          They’re currently pushing for ANOTHER funding increase. Our State reps need to tell them to pound sand.

          I guess those $s that were supposed to speed up the NFA process went to ATF doorknockers.
          Asking about legally purchased FRTs and solvent traps. 🤔

          Repeal the NFA.
          Make the ATF a convenience store a-la 7-11.

        • I’m surprised suppressor manufacturers and retailers aren’t contacting their state reps in DC about the obsurd wait times.

          Why would they? The eFile times are less than the old paper times, so this is an improvement over previous which were around a year, more if you weren’t lucky. Shit, I had a Form 4 take take 22 months back in the first half of the Obama Administration.

          What? You think .gov’s going to get crackin’ and really work for the tax/print money they get paid no matter what the result is? LOL!

          It shows up in <8 months, count yourself the beneficiary of a system that has improved significantly.

  2. I believe the knurled surface is a great aspect of its concept.1st and mostly it’s adding a great amount of surface area to aid in cooling it down faster. not to mention that getting a better purchase on it for removing it after a heavy use day.

  3. Wht would you need a SUPRESSOR in the first place/ you and I both know that if you miss a shot the intended prey WILL DEFINITELY hear your supressed shot almost as clearly as it would unsuppressed, The prey’s very very existence depends on acute hearing way beyond anything human -that’s why PROPER HUNTERS do NOT use supressors because, in real hunting there is NO BLOODY point. And to claim that supressors can improve accuracy is nonsense and you know that perfectly well. ALL supressors reduce MV and that MUST reduce accuracy. Even you csannot ndewfy the Laws of Physics.
    $US 900.00 for what is basically a compltetely unnessessary shooting accoutrement for any conceivable real-world situation is byond my comprehension.

    What’s you commisioin here 25%?
    As they say ‘never give sucker an even break’ even if they are incapable of logical or critical thinking!

    • You know that they’re more for the safety of YOUR hearing not what you’re shooting at, right? Doesn’t really matter I guess since they don’t work too well on a blunderbuss so you likely wouldn’t have a use for one… Or did you finally upgrade to the trapdoor tech?

    • As usual, Albert, none of what you said is true. Literally none of it.

      The main purpose of the suppressor is simply moving your hearing protection from your head to your gun. Making the gun wear the ear pro is much more comfortable, especially if you’re out hunting where you want to be able to hear what’s around you and might fire one time in 6 hours. You’re likely to have to fire too suddenly to put on ear pro first, if you aren’t already wearing it, which is why so many hunters are hard of hearing. Wearing plugs or muffs for hours on end becomes really painful. A silencer is a perfect solution.

      Animals will hear the suppressed gunshot but often don’t know where it came from. Especially with wild hogs, it’s very common for them to mill around in a panicked circle. Sometimes they come towards you. Sometimes they just stand there trying to decide. Even with deer they don’t always run away from the shot. And this is supersonic ammo. With subs they’re far more likely to just stay there and look around and not know what happened and not spook after one shot. None of this is the case unsuppressed. They take off instantly and they go away from you. It’s a huge difference. You’re making a guess about something you have no experience with. I don’t give one flying F what you think the physics should be, because every single hunter who has hunted with and without a silencer will tell you it’s a night and day difference with how the animals react, including me. There’s no comparison.

      Silencers INCREASE muzzle velocity. You’re a moron. This is so well-documented it isn’t even funny. Last time you claimed this trash I showed you my own testing video with before-and-after chronograph results from like 6 different guns. That wasn’t an outlier, it’s how it always works.

      Also, you’re wrong that a change in muzzle velocity necessarily affects accuracy negatively anyway. There is ZERO reason to think that a decrease (or an increase) in velocity will hurt accuracy.

      A silencer usually improves accuracy by stripping gases away from the bullet in a clean fashion as it leaves the muzzle, reducing turbulence around the bullet. Exactly the same reason as why muzzle brakes will often improve accuracy. The weight of the silencer on the end of the barrel also often reduces barrel harmonics, making the gun less picky about specific ammo loads and often improving accuracy with a given ammo load. It also reduces recoil by 50% or so and near completely reduces the concussion from the gunshot, and most shooters will be more accurate because of these things since they’ll be much less likely to flinch and will make a more stable shot with a better trigger press.

      There’s no commission. But even if there were, you think it would be 25 freaking percent? That’s insane.

      You’re a crazy person.

    • Probably depends on the person complaining. Some like smooth cans for the aesthetics.

      Harder use folk know that such knurling is hard on other gear because it’s highly abrasive which means it rapidly wears on softgoods where it contacts them repeatedly. Even cold, such a thing abraids pants, straps, slings, belts, bags, suppressor ovens (mirage covers) etc.

      But it will give you a cool scar if you accidentally smack yourself with it while it’s hot…


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