Ultradyne Mercury Muzzle Brake & C4 Dynamount Sight Combo – Review

Ultradyne Mercury Muzzle Brake
Ultradyne Mercury/C4 Dynamount Sight Combo

U.S.A.-(Ammoland.com)-I was contacted by Ultradyne to see if I would be interested in testing out a couple of their products. They make some very high-end AR-15 parts, and I needed an excuse to build another AR-15, so I said: “why not?”

Ultradyne sent me their Mercury/C4 Dynamount Sight Combo. This combo consists of their Mercury muzzle brake (Ultradyne names all their muzzle brakes after Roman gods), C4 Dynamount Front Sight, and C4 Rear Sight. I couldn’t wait to get them in, so I could install them on my new “work required” AR rifle build.

Ultradyne Mercury Muzzle Brake & C4 Dynamount Sight Combo

When the package from Ultradyne arrived on my doorstep I ripped into the box. I was excited to open it up. When I did open the box, I was surprised at the packaging of the Ultradyne products. I usually don’t write about product packaging, but the Ultradyne packaging was so unique compared to other company’s packaging I must mention it in this review.

Ultradyne packaged each item in what I can only describe as pill bottles. The aesthetics of the design of the packaging is fantastic. Getting the parts out of the packaging wasn’t so fantastic due to how tight the tops were on the bottles. It was pretty tough opening each bottle, but with a little work of squeezing and prying the lid of the packaging, the items finally came free.

Ultradyne Mercury Muzzle Brake

The first part I unpackaged was the Mercury muzzle brake. Ultradyne machined the device out of 416 stainless steel. They then gave the brake a salt bath nitride finish to prevent wear to the brake. It is a solid brake that has plenty of weight to it.

Ultradyne Mercury Muzzle Brake
Ultradyne Mercury Muzzle Brake

On each side of the Mercury muzzle brake, Ultradyne machined three progressive 90° side ports vents for the release of gasses. According to the company these vents spread out the combusting gases. In theory, the spreading out of the gases should cut back on the recoil and muzzle rise of the rifle.

Instead of a one size fits all design Ultradyne engineered this brake for .223/5.56 caliber rounds. Different calibers produce different volumes of gases. By developing this brake for one specific caliber, Ultradyne should have been able to figure out the right math for maximum efficiency for venting the gasses.

I tested the rifle out with a standard birdcage flash hider to get a baseline before installing the Mercury brake. When I redid the test with the Mercury brake, it did cut down on the recoil of the rifle. It seemed the recoil was almost cut in half. The amount of recoil that was mitigated actually surprised me. I knew it should cut down on recoil by just looking at the design, but I didn’t expect that it would cut down the recoil as much as it did.

I decided to do some rapid follow up shots to see if the Mercury bake would cut down on muzzle rise as well. The math said it would cut down on muzzle rise, but the only way to see by how much would be to go ahead and try it out. I started with two quick shots with minimum muzzle rise compared to a standard birdcage flash hider that was on the AR-15 before installing the Mercury muzzle brake. I then fired a set of four shots with a one-second break followed by a second set of four shots. I was easily able to stay on target due to the minimum muzzle rise.

I was actually surprised by how well the Mercury muzzle brake worked. I went through 300 rounds at the range. Ultradyne did a great job on mitigating muzzle rise through some great engineering.

Ultradyne C4 Dynamount Front & Rear Sight Combo

The second item I popped out of its bottle was the C4 Dynamount Front Sight. This item is a front folding sight. The cool thing about this sight is instead of mounting the front handguard like other folding sights on the market the sight mounts directly to the barrel right behind the muzzle brake.

Ultradyne designed the front sight to attach to the barrel because the handguard moves independently of the barrel which could affect the sight’s ability to hold zero. In theory, this small change in the mounting place of the sight should make the rifle more accurate over traditional backup sights.

C4 Dynamount Front Sight
C4 Dynamount Front Sight

The C4 Dynamount Front Sight is also CNC machined. Ultradyne used 4140 CrMo Steel with a salt bath nitride finish along with aircraft grade 7075 anodized aluminum. The sight has some weight to it just in the Mercury muzzle brake. It feels strong as hell.

When designing the sight Ultradyne took inspiration from the concentric sight picture Olympic target shooter use for their sights. Ultradyne uses circle-within-circle sight picture using an aperture that doesn’t block the target. The front sight basically has a ghost ring. They believe that this helps the shooter acquire their target faster than other sights.

C4 Dynamount Front Sight
Ultradyne C4 Dynamount Front Sight uses circle-within-circle sight picture using an aperture that doesn’t block the target.

The C4 Dynamount Front Sight offers the shooter a total windage adjustment of 40 MOA. Each click is equal to 1/2 MOA. Ultradyne also built-in a total of 28 MOA elevation adjustments. Each 1/4 turn is equal to 1 1/4 MOA.

The thing I really like is the shooter can make these adjustments to the C4 Dynamount Front Sight without any tools. A lot of front sights require a separate device to make changes. For an operator in the field that needs to make adjustments on the fly, this is awesome. Ultradyne thought ahead on this one.

The C4 Rear Sight is also a folding sight that mounts to any MIL-STD-1913 Picatinny Rail. Ultradyne made the sight out of the same sturdy material as the front sight. It has the same high-quality feel as the other Ultradyne products I was sent to review.

C4 Dynamount Rear Sight
C4 Dynamount Rear Sight

The aperture of the C4 Rear Sight is a threaded ghost ring completing the circle-within-circle sight picture design. The acquisition of the target using the ghost rings was really quick. I was able to pick up the target and put rounds on it with ease. I really liked the circle-within-circle sight picture design. I also liked how the target was not covered by the aperture.

The shooter can deploy the sight with a single hand. I found it really easy to deploy the C4 rear sight with a single one of my hands. It is critical to be able for a shooter to be able to deploy a sight with a single hand for a good rear backup sight.

Ultradyne designed the C4 Rear Sight with a total of 40 MOA adjustment for windage. Each click is a 1/2 MOA adjustment. There is a total of 18 MOA adjustment for elevation. Just like the front sight, the shooter is not required to have an extra tool to make changes on the fly.

Ultradyne’s C4 sights together work very well. They are a little pricey at $249, but you do get what you pay for with these sights. When accuracy counts, these are the sights that you want on your rifle.

The only change I would make to the Ultradyne C4 Sights is adding some type of spring-loaded rapid deployment mechanism like that of the Magpul MBUS rapid deployment sights.

The Ultradyne Mercury/C4 Dynamount Sight Combo is expensive at $369. This price might be a deal breaker for some, but if you have the extra money, then this combo is fantastic. It is worth mentioning that each of these items is also sold separately at Brownells as well if you only want the muzzle brake or sights for your rifle!

Ultradyne Mercury/C4 Dynamount Sight Combo
Ultradyne Mercury/C4 Dynamount Sight Combo

Customers can find more information about these products and more at the Ultradyne website located at https://ultradyneusa.com

About John CrumpJohn Crump

John is a NRA instructor and a constitutional activist. He is the former CEO of Veritas Firearms, LLC and is the co-host of The Patriot News Podcast which can be found at www.blogtalkradio.com/patriotnews. John has written extensively on the patriot movement including 3%’ers, Oath Keepers, and Militias. In addition to the Patriot movement, John has written about firearms, interviewed people of all walks of life, and on the Constitution. John lives in Northern Virginia with his wife and sons and is currently working on a book on leftist deplatforming methods and can be followed on Twitter at @crumpyss, on Facebook at realjohncrump, or at www.crumpy.com.

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Silver Fox

Someone may be using Ultradyne to hack personal data, so be aware.

Paul Bouchard

Great review. The price seems fair.


Okay, I’ve got to admit (with no small amount of embarrassment) that the name sucked me right in. I have a mercury recoil tube in each of my Glocks and they work great soooo, when I saw mercury muzzle brake I thought, ah hah…..how did they do that? Yeah, should have known! 🙂