New Black Hills Gold 103-Grain ELD-X 6mm ARC: Tested

I should probably start by admitting I’m already a big fan of the 6mm Advanced Rifle Cartridge (ARC). When Hornady first launched the cartridge, it took me no time to get on board with the stubby yet high-performance round. One of the biggest challenges to getting a new cartridge off the ground, though, is getting other manufacturers to load it, so I was thrilled when Black Hills Ammunition announced they would be loading the 6mm ARC with a 103-grain ELD-X bullet as part of its Black Hills Gold lineup. Well-known for premium ammo, if Black Hills likes a new cartridge enough to load it, then it truly brings something new to the table.

For those unfamiliar with the 6mm ARC, it came to fruition by request of an elite group within the U.S. Department of Defense (DoD). Who that is exactly is still secret, but there are only a few possible options based on the criteria they set. They needed a bullet with excellent accuracy and performance to 600 yards that could still fit inside a standard AR-15 platform. The .308 Win. they were using was simply too heavy to carry for their missions, and it wasn’t offering the performance they needed.

6mm ARC Breakdown

The solution was a 6mm (.243) bullet in a necked-down 6.5 Grendel case. A 6mm bullet has a lot of inherent accuracy. They have a high ballistic coefficient (BC); it’s easy to spot hits on steel and in dirt to make shot corrections; and 6mm bullets are incredibly effective on intermediate game and two-legged predators. Simply put, 6mm bullets are a well-rounded close- and long-range option. Loading it into a necked-down 6.5 Grendel case allows it to fit inside an AR-15 and provide performance that traditionally would require stepping up to an AR-10 or bolt gun. The 6mm ARC is arguably the new king of the intermediate cartridge family. It takes the best qualities of the 5.56/.223, 6.5 Grendel, 6.8 SPC and .224 Valkyrie and combines them into one practical intermediate cartridge.

No cartridge is without fault, though. Like its parent 6.5 Grendel case, the 6mm ARC has seen some feeding issues, particularly with home builds. Usually, it stems from being improperly gassed, so an adjustable gas block is imperative for a DIY ARC. It has been finicky with magazines, too, but that again seems to plague home builds more than off-the-shelf factory guns. If you build your own 6mm ARC rifle, be sure to properly gas the gun, then test some magazines on your build and set aside some dedicated 6mm ARC mags the function well. I have not run into major feeding issues with factory guns, and special forces units would not be running guns that regularly malfunction, so I wouldn’t let it put you off the 6mm ARC.

Black Hills 6mm ARC

The new Black Hills Gold 103-grain ELD-X 6mm ARC is a fantastic new addition to the ARC family. I’ve had the chance to try it out with three different guns and on a Texas pig hunt with the new Sightmark Wraith Mini Thermal. But first, let’s break down the new load. Black Hills went with the Hornady 103-grain ELD-X bullet, which is loaded in Hornady’s Precision Hunter line. It has an advertised G1 BC of .512 and sectional density of .249, which is pretty remarkable compared to the other intermediate cartridges.

Hornady offers quite a few caliber options in its Extremely Low Drag eXpanding (ELD-X) lineup. ELD-X bullets feature a unique Hornady Heat Shield which reduces the effects of heating and deformation while in flight, maintaining a high BC. ELD-X bullets are forgiving to shooter error in the wind, making it easier to hit targets at distance with minimal adjustments. While the recorded velocities for the 6mm ARC with the 103-grain ELD-X bullet are on the slower side, it maintains speed and stopping power at distance well. When loaded by Black Hills, the 103-grain ELD-X goes from “just” a hunting load by Hornady to a true multi-purpose cartridge, effective for competitive matches, defensive use and hunting.

Uintah Precision

First up to try out the new Black Hills 6mm ARC is a Uintah Precision 22-inch Upper chambered for 6mm ARC. Uintah Precision builds bolt-action upper receivers that are compatible with either AR-15 or AR-10 lower receivers. It’s a unique way to turn your AR into a long-range platform without building a completely new gun. This upper uses a 1:7.5-inch twist, which is the sweet spot for the 6mm ARC, and performance reflected accordingly. The Uintah Precision upper posted the tightest groups (.5 inch best) and the fastest velocity (2,665 fps) for the Black Hills 6mm ARC, plus it had no feeding issues. If you don’t want to commit to a complete 6mm ARC rifle right away, the Uintah Precision upper is a great way to try out the cartridge yourself. Accuracy and performance is phenomenal with the Black Hills 6mm ARC load, and it would perform especially well in competition or hunting roles.

Shaw Barrels Custom Build 

Shortly after Hornady launched the 6mm ARC, I started my own 6mm ARC build centered around an 18-inch Shaw Barrel with a 1:7.5-inch twist. Shaw Barrels is one of the most underrated barrel manufacturers on the market, and they do an extensive amount of OEM work. Odds are you’ve already shot with a Shaw barrel without knowing it. For the 6mm ARC, 18 inches seems to be the sweet spot for barrel length to velocity. With the Black Hills 6mm ARC load, velocity dropped less than 150 feet per second (fps) while shortening the barrel four inches. Going from 16 to 18 inches provides almost a 100 fps increase with both Hornady and Black Hills loads. While I’ve had some feeding issue in the past with this gun, I had none with the Black Hills ammo using my dedicated 6mm ARC mags. Each round measured with my LabRadar chronograph was right around the 2,500-fps mark, and the Black Hills load consistently has remarkable low standard deviations and extreme spreads for “factory ammo.” Were it not for a few flyers on my part, this would certainly be a sub-moa gun.

LaRue Tactical 6mm ARC

Finally, I tried out the new Black Hills load with my LaRue Tactical Black and Tan Rifle in 6mm ARC. I’ve used this gun at Gunsite Academy rifle courses, Texas pig hunts and general shooting without issue; it’s one of the best rifles I’ve ever used. As expected, the Black Hills ammo performed admirably at the range, but it proved its true real-world effectiveness on a pig hunt in Texas. Sightmark had recently launched an affordable true-thermal optic in its new Wraith Mini Thermal, and I was invited to their ranch use it in person.

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The Sightmark Wraith Mini Thermal on a LaRue Tactical AR-15 with the Black Hills 6mm ARC load is a deadly combination. Three 200-pound boars made their way to a feeder right at dark, but they appeared clear as day with the Wraith thermal. I dropped the first two where they stood at about 50 yards and only needed one follow-up shot on the second pig. The third pig made it to cover but came back about five minutes later. He popped out of the woods about 100 yards away, and I shot him on the run right as he was about to reach the wood line. He also dropped right where I shot him, and I was beyond impressed at the lethality of the Black Hills 6mm ARC load. Big boars are tough animals, so it’s no small thing that all three pigs dropped right where they were hit. One should expect similar results with the Black Hills load on deer, too. At the range, the Black Hills ammo performed well, and it is the best general-purpose gun of the three rifles tested. As expected, there were no reliability issues with the LaRue rifle, and it liked several different magazines tested.

Final Thoughts

Throughout testing, I used a Leupold 6-20X scope in a LaRue Tactical quick-detach cantilever mount, which provides a lot of ease and consistency when swapping between guns. The three rifles used for testing provide a nice spread of use-case scenarios to use the new Black Hills 6mm ARC load, and it performed exceedingly well in each gun. What was intended as a hunting bullet now has great potential as a match contender in a bolt gun, yet it clearly will still perform well on mid-size game.

So, with the excellent performance of the new load, what’s the catch? Well, premium cartridges come with a premium cost. The Black Hills Gold 6mm ARC goes for about $48 for a box of 20, so you’re looking at about $2.40 per round. That’s an expensive plinking round, but for the shots that matter, on a hunt or defending your life, it’s money well spent. That’s exactly how I plan to use it, too, on the shots that matter most. As I said, I’m already a big fan of the 6mm ARC, but the probability it will stick around has been in the air. With the gold stamp of approval from Black Hills, it’s chances of staying on the shelves long-term have just skyrocketed.

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About the Author

Jack Oller is a U.S. Army veteran, having served in the Military Police with one deployment to the Camp VI Detention Facility in Guantanamo Bay, Cuba. He has extensive firearms training from military and civilian schools and is a passoniate shotgun shooter and hunter. Jack has an English degree from Illinois State University, and he started his career in the outdoor industry as Associate Editor for Guns & Ammo magazine. After Gun & Ammo, he worked as Brand Manager for Crimson Trace and now is the Digital Editor for Firearms News.

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