05 August 2023

8.6 Blackout - I'm a Sucker for New Things

 If you haven't heard about it, there's a new cartridge that's been around for a while now. Jokes aside, the boys over at Q LLC along with industry friends had been working on their newest Blackout cartridge and this time they based it on the 308 Winchester. Like they did with the .223 Remington case, Q, Discreet Ballistics and Hornady bumped up the diameter of the bullet and made it longer while trimming back the case. All the same characteristics of the highly versatile .300 Blackout, Q and co gave the 8.6 BLK. The same quiet performance but more of it. 

8.6mm works out to a .338 inch bullet but it's not the same as the 338 Federal. It's wildly different. First, looking at the bullet, the 8.6 BLK is substantially longer. To keep the same overall length to make 8.6 BLK compatible with current 308 Winchester rifles, the case on 8.6 BLK is shortened to 1.68 inches long. The venerable 308 Winchester is 2.015 inches in case length. The extra length bullets means we are seeing massively heavier bullet weights for caliber compared to the contemporaries. Gorilla Ammunition, for example, is producing 300 grain loads for subsonic hunting using Sierra MatchKing bullets. .338 Federal is usually well below that. Granted, those weights are for supersonic loads, the 8.6 cartridge can be loaded to supersonic with similar bullet weights. You likely won't get the same velocity performance from the 8.6 BLK compared to the 338 Federal barrel for barrel but you're not loosing that much. Kurt the Gunsmith did a post on his blog about the differences you can expect here

Where the 8.6 BLK will shine is in shorter guns just like the .300 BLK round does. You simply will not get the same performance from 338 Federal in a short rifle like 10 inches that you will from 8.6 BLK. 

What's also exciting is that this cartridge has a trick up its sleeve. Apparently, in order to stabilize the super heavy bullets, the barrel's twist rate is astronomically fast compared to other more contemporary hunting calibers. The 8.6 BLK uses a 1:3 twist rate. Your usual .308 Winchester is around 1:10. It's not that faster rates don't exist, it's just the fastest rate I've ever heard of in a commercial application. You'll often find 1:7 twist rate in rifles for .223 Remington. The faster rates work with higher ballistic coefficient bullets. The higher the BC, the better they do in flight to retain what velocity they have. 

As it turns out, when you spin a bullet that fast, the bullet will impart additional effects at the target. I would highly recommend watching the video that Faxon Firearms put together. 

The terminal effects on ballistic gelatin are truly incredible. By simply increasing the rotational velocity of the bullet, the terminal wound cavity increases. Now, weather that increases it's ability to take Big Game animals, I don't know, but Kevin Brittingham has been hunting with a short barrel rifle in Africa over the last few years with the 8.6 Blackout very successfully. The biggest downside is that the bullets need to be solid copper instead of traditional lead core as the bullets apparently will spin themselves apart. Many people are already hunting with solid copper bullets successfully so I don't really see that as a downside unless you love casting your own or love cup-and-core construction. I'm using solid copper in my .300 Blackout WWSD AR-15 build.

The biggest benefit the 8.6 Blackout can give the average hunter will be performance with silencers. I have hunted and intend to do so again, with a rifle in .300 Blackout and a silencer. The Hornady SUB-X bullet and factory load was able to successfully take a small doe from short range. I've only taken the one deer but it did work. I'm not sure that the 190 grain SUB-X had the expansion that I want so I've ordered several sleeves of the Discreet Ballistics 188 grain Selous rounds tailored to the 16 inch Remington 700 I've been tinkering with for several years now. I'm interested to see how quiet I can make my setup with a full length silencer. 

DB also makes an 8.6 Blackout load using a bullet that's wild looking. Their Machined Expander bullet design starts to look more like a mechanical broadhead for archery that a bullet once it expands. 

The Discreet Ballistics Machine Expander for the .300 Blackout. 

They have a version of those pills for the 8.6 BLK that I would expect does the same as it does in the .300 BLK. 

Okay. So bottom line, upfront. What reason would make someone run out and buy one of these 8.6 Blackout rifles or rebarrel a .308 Winchester or .243 Winchester rifle? Honestly, nothing the current average American hunter is doing requires it. Where the new 8.6 Blackout shines is for people like me who are trying to hunt with silencers that want to keep things peaceful. Having a dedicated, subsonic hunting rifle that can easily put down a deer without rustling the neighbors jimmies at 8:30 AM on a Sunday morning is a blessing. 

I recently learned that both my Dead Air silencers are able to handle 8.6 Blackout subsonic loads without any issues. The hard part I would have is finding mounts for the KeyMo quick disconnect system as the 8.6 BLK barrels from the current manufacturers seem to not use standard shoulders. Alabama Arsenal has a great video on various silencers on a very short barrel. 

Giving it time, I'm interested in seeing how the new cartridge plays out and what options become available. I do know that Faxon makes barrels for both the Remington 700 platform and AR-10 based guns. Q has a version of their The Fix rifle along with a rifle based on the AR-10. It's like the Honey Badger but bigger. They call it the Boom Box. They have great names for their stuff. 

In parting, I absolutely will be keeping an eye on the 8.6 Blackout cartridge. I would love to build a new rifle to hunt whitetail but as it sits now, the Marlin 1894 and Remington 700 are my go to rifles for taking deer. Maybe in a few years, I can chase this rabbit. 

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