Testing the 22 ARC within the AR15

The 22 ARC is a competition-born cartridge that aims to elbow its way to the top of the gas gun world. The cartridge’s original development strove to propel the most efficient bullets fast enough to make it a hold-and-shoot option for steel-plate matches out to ranges beyond 400 yards. A cartridge that could deliver trajectories rivaling the oft lauded .22/250 Remington, in a standard-sized AR15 receiver, was a winning combination, and its capabilities and versatility have improved further as bullet technology as even heavier target and hunting bullets have been developed. Though it seems that the 22 ARC is simply a necked-down 6mm ARC, it actually pre-dates that cartridge. It began years ago as a necked-down 6.5 Grendel wildcat — notably put to use by competitive shooter and Proof Research’s director of special projects, Greg Hamilton. The 22 ARC has everything a discerning .22-cal shooter wants: minimal recoil, excellent adaptability of the AR platform, and, with the latest high-efficiency bullets, is poised for success.

Shooting Editor John Snow gave us an early look at the 22 ARC and its background in this review, but because gas gun components and production rifles were just getting going in early 2024, we initially evaluated the 22 ARC in a bolt-action rifle. Bolt-action applications of the cartridge do have some surprising potential — including possibly eclipsing cartridges like the .243 Win. — that we plan on covering more in-depth in the coming months. But we were eager to get the 22 ARC on the range in its intended platform, the AR15.

22 ARC Upper or Rifle: To Build or to Buy?

An appealing characteristic of the AR platform is that it is incredibly versatile. In the words of one of my service rifle shooting buddies, the AR is a machinist’s gun. Compared to classics like the M1 Garand, the AR is plug-and-play. It’s simple, universal, and modular. A shooter can buy a whole rifle, parts assemblies, or put together their whole gun from individual components. With a basic armorer’s tool kit or a more extensive one like this one from Real Avid, you can easily assemble or service any of your ARs.

The easiest way to get yourself into a 22 ARC is to simply purchase a complete 22 ARC upper to use with an AR you already have. You can swap it out for your 5.56 or .300 BLK upper in seconds, and all you really need is a specific 6.5 Grendel/6mm ARC/22 ARC magazine.

The number of production 22 ARC AR rifles is on the rise as well. In our 2024 gun test in April, we evaluated a Rise Armament Watchman XR. It was a nice build with good ergonomics, but accuracy was a little disappointing, and the non-adjustable gas block resulted in the gun being overgassed and not always running correctly. It fell short of our hopes for a $1,900 AR.

Ultimately, your own taste, needs, and budget will determine whether you should build from scratch, buy an upper, or buy a whole production 22 ARC rifle, but you can do great with any option.

A Tale of Two 22 ARCs

From the release of the 22 ARC, I planned on testing a gas gun to complement Snow’s bolt-action coverage, but I ended up building two different 22 ARC AR rifles. I’ll detail the builds below, but one was a from-scratch build using an Aero Precision builder’s set, which includes the upper and lower receivers and handguard. I built the other by pirating a very basic AR carbine that I had, installing a 22 ARC barrel and bolt carrier group.

22 ARC Build Number One Specs (20-inch)

20-Inch 22 ARC Build Details

AR parts are dime-a-dozen, so here’s a quick breakdown of why I chose some of these parts and how they worked:

Upper and Lower

I wanted to build an AR with a 22 ARC upper that would be accurate, but also representative of what most DIY AR assemblers would likely put together. Usually, this means a good quality upper, lower, and handguard — all supplied in an Aero Precision builder’s set with a 15-inch M-Lok handguard, along with a standard receiver/barrel nut system. 

Most ARs are set up this way, with the barrel extension pressed into the receiver with an overlapping barrel nut. Most modern handguards are then secured with a few screws or a clamping system to the barrel nut itself. This gives the shooter a free-floated barrel, but because the torsional forces of a long barrel and handguard are all applied at the barrel nut, it can sometimes produce a bit of flex and bugger your accuracy. Service rifle shooters encountered this when first using the AR15 platform in a sling-supported position when the tension of the sling would cause flex in the barrel and receiver. Steel float tubes that ran beneath the handguard were soon developed to mitigate that problem, but some modern precision AR receivers like the Seekins Precision IRMT-3 use a stiffer monolithic upper where the handguard attaches directly to the receiver, not the barrel nut.

Additionally, I added a piece of ARCA rail to the bottom of the handguard to clamp into a shooting tripod.

Barrel and Gas

I chose a 1/7-twist Ballistic Advantage light, fluted DMR 20-inch barrel to hopefully maximize velocity without making the rifle unwieldy with a suppressor. The 1/7 twist is standard for many AR15 rifles, and can handle even the ultra-heavy 90-grain .224 match bullets. 

Learning my lesson from the Rise Armament rifle, I selected a low-profile Odin Works adjustable gas block, which has a click-adjustable gas screw to help fine tune your bolt speed. Through testing I noted that even different factory ammo, ranging from 62-grain to 88-grain bullets cycled at different speeds, and a smart shooter will want the option to adjust that. Installation and adjustment are easy and straightforward.

Stock and Buffer

The Magpul PRS Lite is an excellent choice for a non-collapsing, precision AR stock, and it fits the application of a DMR-style AR that’s suitable for competitive shooting or hunting. Choosing the buffer was a more calculated move. 

When it comes to tuning your gas system to cycle softly but reliably, there are two levers you can pull: reducing or increasing gas pressure via an adjustable gas block or increasing/decreasing the weight of your buffer. If you run under-gassed, or your buffer is too heavy, your rifle won’t want to cycle. If you’re overgassed, like I was when reviewing the PSA Sabre in 6.5 CM, and your bolt is moving too fast, you can break parts, encounter stoppages, or even outrun your disconnector causing double or triple fires. The 5.56 and .223 are quite forgiving in most ARs, but gassier cartridges often need a finer touch. Rather than experiment with different buffer weights such as H, H2, and H3, I chose an Odin Works adjustable buffer that has internal interchangeable weights.

Trigger and Controls

Growing up a 4.5-pound-trigger service rifle shooter, I’ve always preferred two-stage triggers in AR rifles for precision work. There are many good drop-in AR triggers, and I chose Timney’s Targa two-stage model. It has a crisp second-stage stop and breaks at 3 pounds, 13 ounces. In a semi-auto, I like the slightly heavier break and tactile reset.

I also swapped the standard lower parts safety selector for an Odin Works modular ambidextrous safety. This has two tabs on each side that straddle the rotating safety pin, and I offset the right side by 90 degrees so that when I flip the safety to fire, the levers make a perfect resting place for my thumb on the right side of the receiver and help me create a stable and repeatable trigger pull.

22 ARC Build Number Two Specs (18-inch)

22 ARC 18-inch Build Details

In casting a net to acquire the parts necessary to complete my 22 ARC upper and rifle build, I ended up with two quality barrels (the second being an Odin Works 18-inch stainless, heavy-profile barrel). The Odin works barrel came with a rifle length gas tube and gas block. I decided that rather than swap barrels on the same build to test this 18-inch version, I would be better off to cannibalize a generic, cheap build I’d put together years ago with mostly mil-spec parts. 

Changing to a 22 ARC Upper

I’m not sure what make the old upper receiver and M-Lok handguard are, but I easily removed the 5.56mm barrel and replaced it with the heavy-profile 18-inch 22 ARC barrel and gas block. With the right tools, this only takes a few minutes. Adding the Odin bolt carrier group (BCG) with the 6.5 Grendel bolt face completed the picture.

The biggest difference I noted with this “tunable” gas block is that gas is adjusted via a screw in the block that is secured with an additional set screw. To adjust gas flow, you must remove the set screw, adjust the internal screw, then replace that set screw so it doesn’t move. 

Lower Modifications and Bolt Speed Tuning

This was a bare-bones mil-spec build, so I dropped in an extra Rise Armament single-stage trigger that I had around, and after some experimentation, finding that my bolt was running quite fast with a standard carbine buffer. I got another Odin Works adjustable buffer and quickly resolved the issue. 

A telltale sign of a fast bolt is that the cases eject almost straight forward at 1-o’clock in relation to the muzzle. This happens when the bolt begins moving forward before the case can clear the ejection port. That forward motion kicks the spent case forward out of the gun. To the shooter, the feel of cycling will be crisp and snappy.  Conversely, if you are under-gassed or your buffer is too heavy, your bolt will run too slow. Often, a slow bolt will eject cases to the rear, to 4- or 5-o’clock, and case necks being dinged off the brass deflector can be a sign of this. 

Both slow and fast bolt speeds can cause feeding issues and stoppages, and you’ll want to adjust gas and buffer weight to allow the gun to cycle properly and reliably. Generally, a properly-tuned system will feel smooth and eject brass between 2-o’clock and 4-o’clock without damaging case necks.

22 ARC AR Build Results and Performance

I’ve fired both rifles with a variety of suppressors, and found it quite easy to tune the gas and buffer systems to run smoothly and reliably — but big changes in bullet weight seem to make more of a difference in cyclic speed than with the .223/5.56. If you build or buy one, you’ll want to take the time to fine tune it and learn the configuration you need to keep your rifle running in colder temperatures or in dirtier conditions. 

Both of my rifles cycled quite fast with standard carbine buffers, and using a slightly heavier or adjustable buffer will likely tame that down for you.

22 ARC Upper Accuracy

I was underwhelmed by the accuracy of the first 22 ARC AR we fielded at our gun test, but I was impressed by the accuracy these two builds produced. Both averaged sub-inch 5-shot groups with almost every type of ammunition tested. I tested both rifles with three currently available types of 22 ARC ammo: Hornady Black 75-grain ELD-M, Hornady Match 88-grain ELD-M, and Hornady V-Match 62-grain ELD-VT. I also hand loaded 62-grain ELD-VT bullets and 80-grain Sierra MatchKing bullets left over from my service rifle days.

During testing, I recorded many five-shot groups, but also compiled consecutive 20-shot aggregate groups for each type of ammo. We have long leaned on five-shot group sizes for accuracy insight, but have more recently come to realize that it doesn’t give us enough information. Citing a few small-sized groups might make us feel good, but it effectively tells us nothing about the actual limits of dispersion we can expect from a gun.

A 20-shot group size paints a much more precise picture of how a rifle will shoot. Compiling 20-shot aggregates is simple and doesn’t require you to fire 20 shots in a barrel-scorching string. If you’re curious, John Snow details our method in this story here.

Here’s a detailed look at my accuracy and velocity results for each rifle (velocity average of 20-shot samples recorded with Garmin Xero C-1 Chronograph):

20-inch Aero Precision 22 ARC Build

18-inch Odin Works 22 ARC Upper Build

The 22 ARC Advantage at 1,000 Yards

Both of these builds produced impressive accuracy, especially considering their standard barrel nut designs. We test a lot of guns at Outdoor Life, and many bolt-action rifles won’t produce this level of consistency. As I expected, each barrel had its preferences for bullets — the 20-inch barrel seemed to prefer heavy slugs and the 18-inch Odin barrel favored the lighter end of what I tested. Both shot the 75-grain ELD-M factory loads quite well. In fact, it was a field practice session with that 75-grain load and the 20-inch Aero build that turned the light on for me. 

I was shooting steel targets out to 1,000 yards on a blustery day, with 10- to 12-mph crosswinds. As distances increased, I noted the trajectory of the 75-grain 22 ARC bullets (which aren’t even the most efficient for the cartridge) was flatter than that of the 140-grain Sierra MatchKings I was shooting in my 6.5 Creedmoor. I was taken aback when at 1,000 yards, I still had a smaller elevation correction and saw almost exactly the same wind deflection with the little 22 ARC. The difference was that I could watch the trace of the bullet all the way to the target and be ready to send another as soon as it splattered on the steel. Traditionally, .224 bullets are affected much more by the wind.

Here’s a look at the drop and wind drift of the 22 ARC and 6.5 CM factory loads that I was shooting to 1,000 yards in a 10-12mph wind:

Here’s a similar table comparing factory 62-grain 22 ARC hunting loads and a realistic 80-grain hunting handload in a 20-inch AR to some available .22/250, .243 Win., 6mm CM, and 6.5 CM loads with the most similar bullets in factory offerings:

The real advantage that the 22 ARC brings in an AR platform is in the bullets. High-efficiency .224 bullets aren’t new, but they are better than ever. Service rifle shooters have used 80- and 90-grain bullets in .223 AR15s from the 600 yard line, but these bullets are too long to fit in the rifle’s magazine and must be single fed — which compliments the standard slow-fire match protocol. These bullets, and newer bullets like the 80-grain ELD-X and 88-grain ELD-M are even more efficient, and in a 22 ARC, they function and exit at velocities the .223/5.56 cannot match. The 62-grain ELD-VT bullet can be loaded in .223 to about 3,000 fps from a longer barrel, but the 22 ARC pushes the factory load at 3,300 fps from a 24-inch barrel, and still over 3,100 fps in a shorter 18-inch barrel on my rifle.

Like others based on Modern Cartridge Design, the 22 ARC is a cartridge that’s built to launch these heavy-for-caliber, high-B.C. bullets with great accuracy and efficiency. The bullets are the real marvel, but the cartridge that sends them on their way while confined to such small dimensions will have a lot to do with its success. 

Final Thoughts on the 22 ARC AR Rifle

It’s likely that if you build yourself a 22 ARC upper or buy a complete 22 ARC rifle, you might not see better accuracy on paper than a good-shooting .223, and shooting the rifle won’t feel any different. But trust me, once you start guessing and holding on small targets out to 400 or 500 yards with the 62-grain ELD-VT, or shooting the heavier 75- or 88-grain bullets in the wind, you’ll quickly see it pull away from the .223 and even the .22/250. 

You will likely have a rifle that requires a bit of tuning to operate most efficiently, but that’s a small obstacle. I was pleasantly surprised at the accuracy of both of my rifles, considering that they’re so easily assembled. Accuracy, function, and downrange effectiveness are all areas where the 22 ARC seems to shine. It has trajectories and wind drift in an AR that are neck-and-neck with 24-inch-barreled, bolt-gun performance of classics like the .22/250, .243, and within reasonable hunting range, holds close to that of the newer 6mm and 6.5mm Creedmoor. It looks like the 22 ARC has a bright future.