Hornady's 6 mm ARC

posted on April 19, 2023

Hornady has been an innovator in the cartridge world for decades, notably with options like the 6.5 mm Creedmoor in 2007 and several Precision Rifle Cartridges in recent years. One other area where Hornady is developing innovations, though, is within the sphere of military cartridges, and the 6 mm ARC was developed to provide more ballistic capability within an AR-15-size platform. Watch our American Rifleman feature segment above to learn about the development process and capabilities of this round.

"The 5.56 has kind of fallen off the map, if you want to look at ballistic performance beyond a couple hundred yards. Can you hit the target? Yes. Is it going to have much positive effect? Likely not," said Jayden Quinlan, Hornady ballistician. "So you see a transition over to the AR-10 platform to try to make up for that ballistic deficiency of the 5.56. The problem in doing so is now you have a larger system, it's heavier, your capacity is reduced, it's less shootable, it just comes with a bunch of tradeoffs. So what we did with the 6 mm ARC was say, 'what can we do within the AR-15 platform to maintain that size and weight advantage that it has but give it performance that rivals or exceeds that that's found in the AR-10?' and that's essentially the start of where the 6 mm ARC came from."

Hornady 6mm ARC cartridge shown on a white table with a black background.

Following the success of other Hornady cartridges, notably the .300 PRC, the United States Department of Defense approached the company with the request for a cartridge that met a few critical needs. In particular, the round needed to not only work in an AR-15-size rifle, it also needed to have an overall length that couldn't exceed 2.260", be effective past 1,000 yards when fired through an 18" barrel and also allow for a magazine capacity similar to that of the M4 carbine.

"The requirement originally brought to us was we need better lethality without compromising weight. So, we want to get performance but we can't just make stuff bigger and heaver and all those things that you generally do with more 'horsepower,' if you will, from your system, said Joe Thielen, Hornady assistant director of engineering. "That starts with, number one to us, started with the bullet. We had to develop some efficient projectiles to get the performance and accuracy and terminal and trajectory, everything they needed, and that's how we landed at 6 mm."

Hornady 6mm ARC shown on the right compared to the .308 Winchester shown at the left.

Ultimately, Hornady decided to follow the blueprint that led to the creation of the incredibly popular 6.5 mm Creedmoor. Company engineers started with the 6.5 Grendel cartridge case and optimized it for use with Hornady's longer ELD projectiles. The result is a cartridge that can outperform the Grendel at longer ranges while also allowing shooters a wider range of available projectiles that can perform well at shorter distances. The round fit the requirements the military wanted, and it's also become a popular option for precision rifle shooters in the civilian world.

"We had a platform that we had to make something fit, the AR-15-size platform, and we pushed the envelope as far as we could to wring out the last bit of performance out of the AR-15 platform, so that case and that bullet are really optimized to work in that system," said Seth Swerczek, Hornady marketing communications manager. "But it also finds itself really at home in a bolt-action rifle, and in today's precision rifle-type competitions, a lot of the winners are shooting 6 mms running 105- to 110-grain bullets right around 2,800 f.p.s. and what that does is it maximizes external ballistics. You get that really long, sleek, low-drag bullet, you get it out of the muzzle, it's going to buck the wind, you're going to have a flat trajectory, and it really minimizes your recoil, so for the precision-rifle sport, the 6 mm ARC really lends itself nicely."

A man holding a Hornady 6mm ARC cartridge between his thumb and forefinger.

To watch complete segments of past episodes of American Rifleman TV, go to americanrifleman.org/artv. For all-new episodes of ARTV, tune in Wednesday nights to Outdoor Channel 8:30 p.m. and 11:30 p.m. EST.


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