Hornady has expanded its Advanced Rifle Cartridge (ARC) line with a new subsonic-optimized round designed for AR-15 and bolt action platforms. The new 338 ARC joins the 22 ARC and 6mm ARC in Hornady’s continuing effort to modernize hunting and tactical cartridges. But while those rounds are supersonic, the 338 ARC focuses on subsonic performance, while also offering a supersonic option.
338 ARC is designed for military, law enforcement, and hunters, especially those using suppressors. The new cartridge lives in the .300 BLK and 8.6 BLK neighborhood, while offering slightly different, and often superior, performance. Let’s take a deeper look at this exciting new cartridge.
What is the 338 ARC?
The 338 ARC cartridge descends from the 6.5 Grendel, which flashed some military potential early on, but never quite got over the hump. Shooters like it nonetheless, and the 338 ARC is kind of the next generation if you will. Like the 6.5 Grendel, 338 ARC magazines fit the standard AR-15 magazine well, and the new round uses the 6.5 Grendel bolt face. So, 338 ARC upper receivers and bolt carrier groups are compatible with AR-15 lowers, providing great value and versatility to shooters who want to get into it.
Ballistics and Performance
As noted, 338 ARC is intended for suppressed shooting, including tactical and hunting applications. Despite being optimized for subsonic use, Hornady offers a 175-grain supersonic load with a 2,075 feet-per-second muzzle velocity from a 16-inch barrel, delivering 1,115 ft-lbs. of energy at 200 yards and 903 ft-lbs. at 300. The round’s effectiveness drops off considerably past 300 yards. Even so, these numbers are very favorable compared to .300 BLK and 8.6 BLK.
But subsonic is where the new cartridge shines, with its 1,050 fps 307-grain bullet powering out 1.5 times the energy of the .300BLK while being comparable to the 342-grain 8.6 BLK. But keep in mind that the 8.6 BLK’s higher pressures require the heavier AR-10 platform. The 338 ARC does this with relatively lower pressures thanks to its more efficient case, making it suitable for the lighter AR-15. The case design also makes it more effective at longer ranges than .300 BLK.
How Does 338 ARC Compare to .300 BLK?
We’ve noted that 338 ARC outperforms .300 BLK by delivering more energy at short to medium ranges. It retains that energy advantage at 500 yards, though the bullet drop becomes problematic at 118 inches with the 175-grain supersonic load.
Hornady achieved that performance by combining a larger bullet with the more efficient case we mentioned. Subsonic loads don’t burn as much powder as supersonic, which means the case has more empty space, leading to an inefficient powder burn. The 338 ARC’s case is optimized for subsonic efficiency, meaning that extra space is all but eliminated, providing a more consistent and predictable burn.
338 ARC also produces higher pressures (SAAMI Max 52,000 MAP) than .300 BLK, aiding a more consistent burn, and closing the gap between sub and supersonic loads. Your rifle therefore runs more predictably and reliably with each load. That design also drives the subsonic bullet just as efficiently thanks to its lighter weight.
Essentially, 338 ARC does everything .300 BLK does. It just does it better, while also providing a longer effective range. .300 BLK’s sole advantage, right now, is that it’s a more established cartridge, with more load choices and wider firearms compatibility. Those factors will also influence the price, meaning .300 BLK will be less expensive, and more available, for the foreseeable future.
How About 338 ARC vs. 8.6 BLK?
We’ve also seen that 338 ARC is quite comparable to 8.6 BLK, though a bit slower and less powerful across the board thanks to the 8.6’s larger case. We also saw that the 8.6 BLK requires the beefier AR-10 platform, where the 338 ARC is right at home in the lighter AR-15.
But, again, the 338 ARC outstrips the 8.6 in subsonic mode. The bullets are similar, but the 338 ARC’s case makes it a better subsonic choice.
Rifle and Suppressor Availability
As of now, Faxon Firearms, Primary Weapons Systems. and KAK Industry are planning 338 ARC rifles with varying barrel lengths out to 16 inches. Individual upper receivers and barrels are also in the works. The cartridge’s efficiency means you don’t lose much in a shorter barrel, but 16 inches will maximize performance.
338 ARC’s compatibility with AR-15s and bolt guns probably bodes well for future platforms picking it up. And as we mentioned, 338 ARC uppers work just fine on standard AR-15 lowers, so you won’t need a whole new rifle, unless you just want one.
A variety of suppressors exist, assuming caliber compatibility, but the 338 ARC’s pressure rating means you can safely use it with your 9mm cans. No need to rush out and buy something new. Again, unless you just want an excuse to buy one, which is perfectly valid.
And you should fire it suppressed. That’s the whole point. It’s probably the top-performing subsonic rifle cartridge in today’s market. Why not maximize that capability?
Final Thoughts
Hornady’s stated purpose for the 338 ARC was to improve suppressed hunting and tactical applications. In fact, subsonic hunting drove the cartridge’s development. The advantages are apparent. A more capable cartridge paired with a lighter platform is an attractive combination. The same advantages accrue to the tactical side, especially considering the minimal performance loss with shorter barrels.
338 ARC’s performance outclasses .300 BLK pretty much across the board. It’s in the neighborhood with 8.6 BLK, but in a lighter, easier to handle platform. Availability, brand compatibility, and price are the only real negatives right now. That will change if the new cartridge catches on. Only time will tell on that. But the early returns are promising. The potential is there, and Hornady seems to be working hard to expand the cartridge’s reach, if their product page is to be believed.
But in the meantime, options do exist if this seems like something you want to get in on. With suppressors more popular than ever, it’s time that subsonic cartridge performance stepped up. Looks like that time is now.
