.338 ARC Specs
Hornady has been working on this cartridge since 2017, with the goal of producing a mid-range round that will function in an AR-15 platform in either subsonic or supersonic versions. It must also function suppressed or unsuppressed and be accurate and efficient.
To meet these goals, Hornady selected a larger case based on the 6.5 Grendel that holds more powder than a .223 brass cartridge. The .338 ARC seeks to cure the shortcomings of other subsonic AR-15 rounds and will function in my AR platform rifle in supersonic and subsonic loads. It does so by using a propellant that fills the case fully.
The case is mated to one of two bullets, each intended for a specific use.
Subsonic:
- The Hornady Subsonic 307-grain Sub-X delivers 1.5 times more energy than other similar rounds. The polymer-tip hollow point expands reliably at velocities as low as 900 FPS. This round is limited to hunting medium-sized game at about 100 yards.
- Cartridge length: 2.206 inches
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Velocity: 1,050 FPS
Supersonic:
- The Hornady Black Supersonic 175-grain is a hollow point, flat-based round that delivers competition accuracy beyond 300 yards with manageable elevation drop.
- Cartridge length: 2.244 inches
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Velocity: 2,075 FPS
A Versatile Load
I like using one rifle for various tasks. The .338 ARC cartridge allows me to use one AR-15 rifle or carbine for hunting Arizona javelina or varmints at close range with excellent downrange retained energy. I can simply change to the target load in the same rifle for action shooting events and mid-range target shooting.
Sighted in at 200 yards, the Hornady Black .338 175-grain target load will be 4.2 inches high at 100 yards and only 16.3 inches low at 300 yards. With a proper riflescope and target reticle, I can hit steel targets at longer ranges by simply holding over.
In either cartridge velocity, the .338 ARC is suppressor friendly. There is no need to tune my semi-automatic rifle for shooting suppressed or unsuppressed, as the ARC round is balanced to shoot accurately either way. This is not an easy task, because it involves matching the correct powder charge with the proper bullet. Jams will result if this is not accounted for properly.
My Setup
The CMMG Dissent Mk4 is just the rifle to test the Hornady Black .338 ARC cartridge. CMMG’s patented Compact Action operating system uses a bolt carrier group mounted on dual guide rods that allow the entire action to be housed in the upper receiver. Since there’s no buffer tube, the stock can fold, making the rifle short and easy to transport or shoot from the hip.
Related Review: New CMMG Dissent in .338 ARC – Quiet, Hard-Hitting Firepower
I've outfitted the rifle with a SilencerCo Hybrid 46 suppressor (see more on this can in the review linked above) and Winchester Supreme Optics 6-18x50 riflescope with illuminated reticle. This scope has clear optics and has proven to be repeatable for both windage and elevation. It will bring out the best of the .338 ARC.
Related: Will a Suppressor Affect My Shooting Accuracy?
SHOOTING TEST
Shooting from an action range long bay at the historic Tucson Rifle Club of Tucson, Arizona, I will test five-shot groups on a steel target at distances of 100, 200, and 338 yards. My milk-bottle shaped steel target is 27 inches tall by 12 inches wide and is suspended 4 feet above ground level. I can see my hits better on steel than paper.
Starting at 100 yards, I’ll shoot from the bench using my rifle rest with sandbagged stock. The Winchester scope easily focuses to match the distance with its parallax knob. Elevation is set to “0” for this distance on the scope.
At 200 yards, I readjust my scope and increase the power magnification factor to “10” to bring the target into focus. Elevation is set to “5” on the turret.
Finally, 338 yards will be the ultimate test for the 175-grain .338 ARC bullet. My elevation turret is set to “10” as I focus parallax for this longer distance. Even at the max magnification of 18X, the Winchester Supreme Optics riflescope focuses clearly on the steel target.
Results
Keep in mind, these groups were fired from a small utility table on the action range of my club, which I feel is a practical test for the ammo and rifle platform. Although a concrete table and solid rest might have yielded tighter groups, this is not always possible in the real world. Action shooting frequently requires impromptu shooting positions.
Five-shot groups:
- 100 yards: 1.5 inches
- 200 yards: 3.5 inches
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338 yards: 4.5 inches
GARMIN Xero C1 Pro Chronograph results with .338 ARC Hornady Black 175 grain HP and CMMG Dissent 16-inch barrel, suppressed:
- Five-shot average: 2,098.9 FPS
- Extreme spread: 18.5 FPS
- Standard deviation: 6.6 FPS
These numbers prove that Hornady has delivered on its promise to make a cartridge with great shot consistency. My goal is to hit steel every time, and the .338 ARC and CMMG Dissent combination is a match for the challenge.
PROS & CONS
