8.6 Blackout vs. .338 ARC: Big Bullet, Quiet Shots
June 17, 2026Posted by derrek.sigler
If there’s one thing true about gun guys (and gals), it’s that we like to talk about guns. We are always interested when something new comes out. And yes, these talks can get heated from time to time. There’s always going to be that one guy that shouts at the top of his lungs that there isn’t any cartridge that can do something his (insert name of older cartridge here) can already do. Okay. But... The cool thing about new cartridges is that there is a lot of room for specialization. Case in point - the 8.6 Blackout and the .338 ARC. Both have some similarities, but they are definitely NOT interchangeable, and both were designed for a specific performance standard. Let’s explore.
Both cartridges throw .338-caliber bullets downrange. They both work exceptionally well with suppressors, and both are designed to deliver impressive performance from relatively compact rifles. That's where the similarities end.
8.6 BLK
The 8.6 Blackout was built with one goal in mind: maximum thump from a short barrel. Developed by Q, it uses a shortened 6.5 Creedmoor case and excels at pushing heavy bullets, especially in subsonic loads.
The cartridge was designed from the ground up for suppressed shooting. It is a favorite among hunters. It provides serious terminal performance without the blast of traditional magnum cartridges. Even from barrels as short as 8 to 12 inches, the 8.6 Blackout hits hard and delivers decent energy on game at practical hunting distances.
Looking for a suppressor for your 8.6 BLK?
Dead Air’s Nomax 33 is a 3D-printed titanium silencer that meshes light weight with quiet shooting. It is just 9.6 inches and weighs 15.4 oz with the included Xemax adapter. The Nomax 33 is sized for optimal sound suppression and excellent tone, while the titanium construction keeps the weight to a minimum. Being a .338-caliber suppressor, the Nomax will work on any caliber firearm below that. With your 8.6 BLK, and subsonic ammo, this would make your rifle quiet. Real quiet.
The .338 ARC takes a different route. Hornady designed it around the AR-15 platform, using the same case family as the 6mm ARC and 6.5 Grendel. The result is a cartridge that offers excellent subsonic performance while still providing useful supersonic capability. Because it fits standard AR-15-sized rifles, shooters get lighter guns, greater magazine capacity, and less recoil than the larger 8.6 Blackout.
The fun thing about .338 ARC is that you can build one yourself rather easily. In fact, you can spend a lot on a build, or very little. I have a spare receiver sitting in the safe that I'm probably going to build. If I go on the cheaper side, my wife may not notice it on the statement as much. You have to think these things through.
Ready to suppress your .338 ARC rifle?
SilencerCo ‘s Hybrid 46M is a light, compact, and modular centerfire rifle suppressor. It is made of stainless steel, titanium, and Inconel to offer unrivaled compatibility. A removable front module on the Hybrid 46M provides the shooter with a shorter and lighter suppressor body for situations where size and maneuverability are of utmost importance. You will get a lot of flexibility to use this on your .338 ARC as well as just about any other gun you can throw in the safe,
Side by side, it is easier to see how vastly different these two cartridges are. Thanks to our friends at Guns & Ammo for taking this photo, too!
For many shooters, the decision comes down to intended use. If you want maximum stopping power from a short, suppressed rifle and don't mind stepping up to a larger platform, the 8.6 Blackout is hard to ignore. If you'd rather stick with an AR-15 and want a cartridge that balances efficiency, versatility, and suppressor-friendly performance, the .338 ARC makes a compelling case.
Neither is wrong. They're simply two different answers to the same question: how do you get big-bore performance from a modern suppressed rifle?
Yes, I’m going to bring up the .338 Federal again
The year was 2006. I heard about a new cartridge being developed by Federal Premium Ammunition. It took a .308 case and necked it up to accept a .338-caliber bullet. Thus, the .338 Federal was born. Federal developed the cartridge as a factory version of the wildcat .338-08. It was part of a collaboration between Federal and Sako Rifles. Where they won me over was with the ballistics. It beat out the .308 WIN, with 200–250 fps more velocity using the same bullet weights. It exceeded most loads of .30-06 energy levels within the 300-yard range.
At the time, I was suffering from a debilitating condition called Alaskaitis. In fact, I still live with that condition every day of my life. You might have it, too. The symptoms are a burning need to go back to Alaska to fish and hunt. If you haven’t gone, don’t go. Save yourself the pain of getting to go there and then being forced to leave. You’ll just spend the rest of your days trying to figure out how to go back. Anyway, back to the .338 FED. I saw this new cartridge and immediately started thinking. How awesome it would be to have an AR-10 platform in .338 FED? I even had a title for the story, “ARe You Ready for Moose?”
Alas, my dream of hunting moose with an AR-10 in .338 FED never came to be. I kept it in the back of my mind, though, and was always working toward it. There were some truly nice rifles being chambered in .338 FED. But that number slowly dwindled. Right now, Wilson Combat seems to be the only source of new .338 FED rifles and uppers. Sadly, I don’t make Wilson Combat-kind of money. In fact, right around the time I had finally pulled together enough resources to make my moose hunt happen, my wife hit me with some news that has derailed many hunter’s dreams of adventure. Yes, my daughter is better than a moose hunt. Being a grown up is rough.
The 8.6 BLK is based on a 6.5 Creedmoor case, shortened and necked up to accept a .338-caliber bullet
Yes, you can, but with different platforms. The 8.6 BLK will work in an AR-10 platform because it uses the 6.5 Creedmoor case and bolt face. The .338 ARC was designed to work in an AR-15. You just need to swap in a .338 ARC upper.
At close range, it delivers a bigger bullet and if you load subsonic and use a suppressor, it is extremely quiet. Once the range starts to extend, however, the .308 WIN takes over.
The .338 ARC was built off the 6.5 Grendel case. It adds a much bigger bullet option with the versatility of the AR-15 platform.
While many suppressors can be used on several different caliber firearms, we have some specific models that can make your shooting more enjoyable. Pick the caliber that you have in mind. If you don’t see your caliber, pick one close to it to see our recommendations.
