Hands-On: Ultradyne C4 Dual Aperture Sights

If you’re looking for iron sights that allow fast target acquisition and precision- you’ll want to look at the C4 Dual-Aperture sights from Ultradyne. And there’s more to these sights- they also feature ballistic drop compensation!


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I’ve had several decades of experience using “iron” sights of various configurations in various settings. I’ve used rifle sights in the USMC, SWAT/Police duty, formal target competition, informal plinking, and hunting. Though optics have gotten more rugged and better over the years, they can still fail or a zero can be off. It’s very important to have a backup instantly available on the rifle.

This wasn’t my first experience with dual-aperture sights. In the 1990’s and early 2000’s I used a Winchester Model 70 match rifle in prone competition with a Tiger front sight. This sight had interchangeable apertures of different sizes. The rear sight was a Swenson with an adjustable aperture. The target was a round bullseye; the front sight was a circle; the rear sight was a circle. My eye had no trouble centering the target in those two concentric circles and I shot some good scores that way — better in fact than I did using the same rifle with a scope on it! 

I was pleased to see that Ultradyne had brought the dual aperture concept to a set of rugged, lightweight and very useful backup rifle sights. In a defensive-type rifle they allow for quick acquisition. A sight problem I’d first noticed in the Marines was that at 500 yards, the human-sized silhouette actually appeared smaller than the front sight post of our M-16’s! This was something my then young eyes could cope with. Most of us shot those rifles well. In law enforcement, our AR-15 Patrol Rifles had a post front sight, which I found could conceal part of the target, possibly keeping important information like possession of a handgun or knife by the suspect from the officer. The C4 dual aperture sights allows you to focus on the target if you need to (though marksmanship preaches front sight focus) and your eyes naturally want to find center.

C4 Dual Aperture Sights Overview

About Ultradyne Dual Aperture C4 Sights

From ultradyneusa.com:

The C4 Front/Rear Sight Combo is a dual aperture sighting system that is changing the way shooters think about iron sights. The C4 Rear Sight offers Rock-solid performance in a compact form with a ballistically calibrated elevation system that adjust in 50-yard increments from 200 to 600 yards. The C4 Front Sight brings precision front aperture technology to backup iron sights along with the ability to adjust both windage and elevation. Using these sights together creates a perfectly concentric sight picture that allows the shooter to see the target, enables faster sight acquisition and gives the ability to consistently shoot accurately out to 600 yards and beyond. All with compact, foldable iron sights

The rear sight aperture is threaded and can be easily removed without tools. Ultradyne offers apertures in both 0.070” and 0.050”. The aperture can also be removed completely and used as a generous ghost-ring type sight. 

Beyond the dual aperture, there are other reasons to appreciate these American-made Ultradyne C4 sights. They’re lightweight and compact, adding very little bulk or weight to the rifle. I prefer an AR-15 defensive-type rifle to be lightweight and fast handling with few “gadgets” attached. Keep it simple — there are fewer things to break. The sights fold down easily, reducing the chance of banging one on something. They also quickly flip up into position using just one hand. This can be important in a defense situation! 

Ultradyne’s C4 folding front and rear sights appear to be well-made and virtually rust-proof. Constructed of 416 stainless steel with a salt bath nitride finish and 6061-T-6 hard anodized aluminum, these sights are both lightweight and durable. The front sight weighs only 1.3 ounces and the rear just slightly heavier at 1.7 ounces — far less than many tactical type scopes and mounts.

A terrific feature of these sights is what could be called a BDC or Bullet Drop Compensator. This is something we’re accustomed to in scopes and other optics, but it works great on these sights as well. Ultradyne builds these sights in two configurations: one calibrated for the M193 5.56 cartridge sending a 55 grain bullet about 3,100 fps; the other is calibrated for the 7.62 M80 cartridge with the 146 grain bullet at about 2750 fps. 

It works very  simply. Once the rifle is zeroed at 200 yards, simply dial the knob on the rear sight to 2, 3, 4, 5 or 6. Each number times 100 equals the distance: 200, 300, 400, 500 or 600 yards. There are also intermediate stops every 50 yards all the way to 600. 

In order to understand why dual aperture sights work, let’s first look at different aperture and depth of field scenarios which are outlined in this diagram:

Some advantages for dual aperture sights become clear when we look at the above concepts:

  • By looking through 2 apertures your brain tells your eyes to acquire the target more clearly
    • If you were to look at a sign at a far distance that you could barely read – you should be able to read it a lot easier through the 2 apertures
  • The natural connection between the brain and the eyes is enhanced looking through 2 apertures.
  • Dual Aperture suppresses parallax (or alignment error) better than traditional sights because it constricts the pupil and enables focus on target. (as outlined in the diagrams above)

Now on to testing these sights!

Our Test Scenarios

I installed the sights on both a 5.56 AR-15 and a 7.62 AR-10. The sights were easily mounted on the MIL-STD-1913 Picatinny rails. I had quite a bit of good quality IMI 5.56 55 grain ammo on hand as I headed to the rifle range. 

Following the instructions from Ultradyne, I zeroed the AR-15 by sighting it in 1.4” low at 25 yards. That translated to .4” low at 50 yards and zeroed at 200 yards. It may be prudent to make final adjustments at 100 or 200 yards to center up the group. 

After setting the zero, I shot the rifle on steel at 25, 100, 200 and 300 yards. Some of my shooting was from a bench, some of it was CQB (close quarter battle) type training in the UR industrial yard. I found the sights very quick to use and it was easy to put rounds on target.

Reporting those results to Gavin, we decided I should give the 400 yard “steel coyote” at the Ultimate Reloader ranch a try. The sunlight was striking it at an angle that rendered the white target nearly invisible to the naked eye! I found the target through my binoculars then asked Zach to spot for me while Tyler flew the drone to observe the target. 

I had noticed my groups were just a bit high while shooting at 100 and 200 yards. The steel coyote was above me and 400 yards away, so I dialed the rear sight to 350 yards and secured the rifle in a Bog “Death Grip” hunting tripod. The first shot was a bit low and left. I simply nudged my sight picture a little — still looking through the sights right at the steel coyote — fired again and hit the target! That always brings a smile to my face. 

For the AR-10 testing, I used one of CMMG’s impressive Endeavor rifles. However, we had some problems with the 308/7.62 ammunition we had on hand. The rifle and ammo available just didn’t want to work together, so we swapped on a 6.5 Creedmoor upper and gathered up some Federal Gold Medal ammunition loaded with a 130 grain Berger bullet. 

I performed the same shooting drills with the 6.5 Creedmoor, except that I only took it to 300 yards, where I had no problem banging the steel gong. At least out to 300 yards, there didn’t seem to be enough difference between the trajectory of the 130 grain 6.5 Creedmoor and the 146 grain 7.62 ammunition to matter with these sights. BTW, most commercial M80 equivalent ammunition is loaded with 150 grain FMJ bullets — close enough I think! 


The Ultradyne Dual Aperture C4 Sights have a host of features: 

  • Dual Aperture (front and rear)
  • Interchangeable apertures or even Ghost Ring
  • BDC type elevation adjustment on rear sight
  • Easy flip up & fold down with one hand

Compact: The pair of sights adds only 3 ounces of weight to the rifle and folds down flat on the Picatinny rail when not in use. 

Versatility: I liked these sights as much in the CQB drills from 7 to 50 yards as I did at 100, 200, 300 and 400 yards. Gavin shot the 5.56 with Ultradyne sights at CQB distances in the UR Industrial Yard and concluded that they were terrific for that purpose.  I’ve no doubt that they will work fine out at 600 yards as advertised by Ultradyne. One set of sights that’s good at both fast-paced short range shooting and also at longer range — that’s versatile! 

BDC type dial: This is such a useful feature! Range the target at 400, dial “4”, then take the shot! 

Quality: These sights are high quality sights made here in the USA — a distinct step above some of the BUIS sights on the market. The materials, nitrided stainless steel and anodized aluminum, are tough. The design of these compact sights is unique and very useful at close distances and out to significantly longer ranges. 

Get the Gear

I want to note that Ultradyne has a terrific web site with a lot of information regarding their products and how to use them. The web site is backed up by an impressive presence on YouTube with “how to” videos.

Ultradyne – Home | Buy American Made Gun Accessories for Your Rifle (ultradyneusa.com)

Ultradyne – YouTube

The sights retail for $299 on Ultradyne’s website: 

C4 Folding Front and Rear Sight Combo – Ultradyne (ultradyneusa.com)

I’ve found them at a reduced price at Brownells and other online sources: 


Bog Death Grip tripod: 

Death Grip Gun Tripod Clamp – BOG-Pod, Aluminum, 72″ Max (midsouthshooterssupply.com)

Federal Gold Medal 6.5 Creedmoor ammunition: 

6.5 Creedmoor 130 Grain Berger VLD 20 Rounds by Federal (midsouthshooterssupply.com)

IMI M-193 55 grain FMJ ammunition:

IMI Ammo 5.56x45mm NATO 55 Grain M193 Full Metal Jacket (FMJ) Boat (midwayusa.com)

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Guy Miner

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