Looking to put together a 8.6BLK bolt gun. Anyone here have experience between 8" and 12" barrels?

Everything I've been able to find on the cartridge says 12" is ideal for ballistics, but my heart keeps taking me to 8"

Hoping someone's got some insight to point one way or the other.


Will be on a Aero solus action and either a 7.5" Aero chassis or Black Collar Arms Pork Sword chassis. Aesthetics push me toward the pork sword w/12" bbl or Aero with 8" bbl just so the can will sit relatively flush with the rail.

I built mine right when Faxon came out with their Remage barrels, my barrel was 12" to start.  I bought a Remington 700 in 308, did a from 1, and with some gauges barreled the action.  I'd already ordered the Pork Sword before starting the build, and it took about a year for that to come through and I ultimately really disliked their stock.  I used the factory synthetic stock cut back to clear the short barrel until the PS finally arrived.  

I shot up a good amount of Gorilla supers and subs to break it in and get some brass to reload.  I have also converted a bunch of Hornady 6.5cm as well.  My original plan was to load both supers and subs.  After trying to push some supers to the velocities that I wanted to see, it was clear I was never going to get there with 12", so I had the barrel cut back to 8" and threaded for 5/8-24 20* taper to work with the Porq Chop.  The original M18x1.5 20* threading is a pain unless you're only going to run Q cans.  They have XL Cherry Bombs in both threadings now, so the 5/8-24 with taper works best for other mounting systems.  Going to 8" has got me ideal velocities for all the subs I've loaded, 225-350gn, plus its so much more compact.  

Ultimately, I'm not quite getting the accuracy out of the Faxon that I think the cartridge is capable of.  I am getting right at MOA with the 300smk, and 1.25 with the 280 Discreet expander, but with super low single digit SDs so I think groups could be better.  I ordered a 16" 1:3 Shaw barrel, and its at the gunsmith right now getting cut back to 8", threaded 5/8-24 20* and chambered since its long chambered and shouldered, not a Remage.  

I shot a ton with my Hybrid 46 and a 9mm front cap while I was waiting for the Porq Chop to be approved.  It worked well, but the PC is on another level sound wise imo.  Its a challenging cartridge to load for, limited info and you have to be careful to keep non-bonded or mono projectiles from spinning apart with too much velocity.  When its working right though, those 300gns slamming into steel is really awesome.  I'm hoping to take the 280 Discreet expanders hunting in the fall, we'll see how the new barrel shoots.

If I had this to do all over again, I'd absolutely buy the 8" Fix to start, especially now with the free can promotion they're having.  With what I've spent on the project, I'm still under the cost of a Fix, but its really the easy button.  I have a Mini Fix SBR in 300bo, and while its over priced, the form factor is awesome, and impossible to match with any build based on a normal bolt action receiver.  I put a Fix stock on the Pork Sword with a Q hinge because its so much better than what Black Collar is offering.

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rather than cut back to 8", do it a bit longer so you have the option to pin and weld a suppressor to make it 16" and get out of the SBR tax.  if you planned to always use a suppressor in it, it's a no brainer IMHO, especially with how fast they are turning around form 1's and 4's

How much recoil does it have with supersonics? Given that it has none with subsonics.

Thats an amazing writeup, thank you @turbobrick !  I LOVE the idea of a folding stock that the pork sword allows, and right now the aero doesn't.  But I can get the aero chassis for significantly cheaper than the pork sword.

Appreciate your insight on the reloading front as well. I'm definitely going to be loading this cartridge and was operating under the assumption that I'd be loading both subs and supers, thus would be utilizing that extra barrel length for velocity. Reading your post and thinking about it, I might be best served sticking to subs anyway... If I wanted to sling full speed projectiles, I'll probably use a different cartridge. This rifle is going to be more for grins and banging steel.

It has enough recoil that supers were not fun with the original Pork Sword folding stock or the original Fix pad.  The Pork Sword pad is very thin, and the Fix is nearly solid.  In both cases the recoil was fine, but distracting.  Would not be a problem for hunting, but you need more pad if its going to be for volume at the range.  I put the big pad from Q on the Fix and forgot about recoil.


I have seen some guys go into the way lighter end of .338 down in the 160s and they are getting up into 2100fps which is amazing given what they're working with.  But for me, I have a 338-06 that will do way better with the same projectile, and I don't have to try and resolve the drastically different POI and dope that comes with the super-sub gulf in 8.6.  When you reload, I'd highly recommend VHT N110, its been the best powder, many of the other popular powders are geared toward semi-autos and end up much louder than they need to be in a bolt gun.  Midway and Shooters Pro Shop consistently have blemished 338 projectiles, I'd start picking up stuff in the 280-300gn range for plinking, and definitely the Discreet if you intend to hunt with it at all.  The 350 Maker expander is really cool in concept, but I haven't seen anyone who has got them shooting really well, a few MOA at 100 at best.  Good luck on your project, let me know if you have any other questions.  There is a pretty detailed thread on Snipers Hide in the reloading section that has a good amount of info, and a ton of marginal at best info, have to read critically.

Solid points on the supers. I'm pretty much convinced the 8" is the way to go now. N110's an easy sell as well- I've used N110 and N120 for 300blk so it's not surprising that it would perform well in another blackout cartridge. Makes me wonder if SW SBR SOCOM would be a decent powder, too (or their BLACKOUT powder).

Other than building the gun, I need to get smart on which brass is best to use for converting that doesn't require neck turning. I see one thing that says use Hornady 6.5, then immediately read another that says its not going to work. This will be an adventure, but a fun one.

How 'bout you split the difference between 8" and 12" and get a 10" barrel?

A little bit shorter than 12", a little bit more velocity than 8"... more powder burned vs. 8" means quieter and suppressor performance goes up... compromise is crazy, right?

That would be a very reasonable choice and is an outstanding suggestion. But...I've got a line on a couple very cheap barrels and those are my options. If 10" was available, I'd be very inclined to split the difference.

I had good luck with CFEBLK and Titegroup as well.  None of my local dealers have Shooters World, but I am really interested in, and searching for, some of their powders to try in 6arc.  I think many of the faster pistol powders will work great in 8.6, I did find pressure with the 350 Maker and TG though, I wasn't even thinking that was all that possible with subs, it kind of surprised me.

At the time I converted brass, there was no virgin brass available.  It was a pain in the ass, much more labor intensive than 300blk.  I still had to turn some of the necks even though I used Hornady 6.5cm.  I still save any Hornady 6.5cm I find at the range, and I will convert it later on in a big batch.  I mostly use the converted brass for plinking ammo.  If you're going to convert brass, I highly recommend getting the cut away gauge from Sheridan, it'll tell you right where your problems areas are.  I also like the Little Crow trimmer if you don't have something like a Giraud.

Now, Gorilla sells their brass which is made by Starline, Q sells their brass which is made by Hornady, and Alpha is selling some really nice looking brass.  If I had it to do again, I'd just buy brass, or watch Gunbroker, I bought a big lot of once fired Gorilla and Q brass.  

I disagree, you don't need any more velocity.  I can get the 350 Maker to 1050 in 8", any faster and it supersonic.  When you're staying subsonic, velocity has a ceiling, and if you're using the right powder, its all burned before 8", and that usually shows up as really low SDs.  I think I could still do everything I want with 8.6 with maybe even a 6" barrel, and it would still sound the same.  Now, a ton of people are running 1680 in 8.6, and at 8" its not all burned up, and that is a loud combo, a good portion of that powder is burned after the bullet is out of the barrel.

I went back through my reloading notes to see if I could be more scientific about supers.  In my Pork Sword, factory Gorilla with the 210 Barnes was 1997avg out of the 12" barrel.  I tried the Hornady 185CX in converted Hornady 6.5cm brass with WLR and 1680, the best I was able to do was 2160 and I found pressure right after that.  It probably could be pushed higher with a different powder or something like the 175 Hammer, but most of the monos really need an impact speed over 1800, so you're talking about a pretty short range hunting gun.  The Q/Faxon load chart shows them getting 2200 out of a 160 Barnes in a 12" barrel, so I feel like I was right in the pocket, there just isn't enough barrel to get much over that 2200 mark with any weight projectile.  Personally, I'd rather have a really heavy subsonic that I know is going to open up than a borderline too slow super with questionable expansion for up close rifle hunting, not to mention how much quieter the subs are.

Youve got me sold on the subs brother

I use 300blk because its versatile in both super/sub loads. But after some consideration, this one’s really just to throw big heavy bullets quietly. With that in mind, I ordered a 8.3” barrel and a chassis.

Now I’m just working on deciding that can it’ll get. TBAC seems pretty well liked, as well as the porq chop (but not liking their mount). Or CGS, or diligent defense. Rex seems good too, but theres nothing out there for reviews so I’m not sure how quiet it’ll be. YHM also has a new “bad larry” 338 can, but after watching their video in it…im kinda unimpressed. I’ve never really chased decibels before, but for whatever reason, I’m really looking forward to it with this bolt gun.

Really appreciate your insight man!

Seeing how my AAC 762SDN6 sounds unreal with 300blk, I stuck with KB for his 8.6 can too, but the mount is a definite drawback.  When I was shooting some of the other subs from Gorilla with my Hybrid 46, they were pretty inconsistent with poor SDs, so getting hits on steel at 200 was a challenge, and for some reason 300 was out of the question, I wasn't even able to see impact some of the time.  Fast forward to my Porq Chop being approved, and I immediately could hear the problem.  My local range has a 'no blue sky baffle system', and with the gun angled up for 300 yards, the projectiles were clipping the wood barrier 15 yards out and 10 feet up, sending them who knows where.  I never heard that with the Hybrid, but I heard it instantly with the PC, I think it's suppression is just so much better.