Springfield XD Forum banner
1 - 13 of 13 Posts

·
Registered
Joined
·
20,051 Posts
Discussion Starter · #1 ·
Anyone see much about this round? It's basically a tweaked 338Fed with a stupid fast twist rate of 1:3. It look like they are claiming that the rotational velocity will dump more energy on target. Thoughts?
 

·
Registered
Joined
·
1,334 Posts
I think you're thinking of 8.6 BLK, not 6.8. Unless they've created another Blackout round. I heard about 8.6 a while ago, but haven't heard a whole lot since then. I think it was conceived before Covid and then everything hit the fan, so it was kinda forgotten. Maybe now that things are getting back to normal, it'll come back into the light.
 

·
Registered
Joined
·
20,051 Posts
Discussion Starter · #3 ·
I think you're thinking of 8.6 BLK, not 6.8. Unless they've created another Blackout round. I heard about 8.6 a while ago, but haven't heard a whole lot since then. I think it was conceived before Covid and then everything hit the fan, so it was kinda forgotten. Maybe now that things are getting back to normal, it'll come back into the light.
Yes. 8.6. I corrected the title (I think)Looks like Faxon may be driving it? I guess I don't care too much about the specifics, but more about the fast spin thinking.
 

·
Registered
Joined
·
231 Posts
I think the fast spin is really interesting too, but I'm not sure how well that will translate into mainstream uses just from a practicability stand-point.

Q and Faxon seem to be hailing this as the 300 BLK of the AR10 platform and will be offering barrels for the AR10 and Rem 700.

I'm a fan of 300 BLK, but that's because I think a .30 cal in an AR with just a barrel swap is a great idea-- which appealed to a lot of people who wanted AK-like ballistics in the AR without compromising reliability or function or those who wanted (as close to) .38 SPL lever gun/.22 LR rifle quiet in an AR.

That being said, I'm not sure I get the cost justification to jump to 8.6 BLK from any other standard center fire round available in the AR10 or Rem 700 (or similar bolt action)-- especially since the market is almost saturated with choices: .308, 6.5CM, etc. Could it out perform these other cartridges in one way or another? Sure. But how much more is each round going to cost for the first few years of onboarding (or indefinitely)? Further, the AR10 seems to be a little more niche than the AR15.

If it catches on like the 300 BLK did after a few years, I may reconsider, but right now I have my doubts about the cost to benefit ratio.
 

·
Registered
Joined
·
20,051 Posts
Discussion Starter · #5 ·
I think the fast spin is really interesting too, but I'm not sure how well that will translate into mainstream uses just from a practicability stand-point.

Q and Faxon seem to be hailing this as the 300 BLK of the AR10 platform and will be offering barrels for the AR10 and Rem 700.

I'm a fan of 300 BLK, but that's because I think a .30 cal in an AR with just a barrel swap is a great idea-- which appealed to a lot of people who wanted AK-like ballistics in the AR without compromising reliability or function or those who wanted (as close to) .38 SPL lever gun/.22 LR rifle quiet in an AR.

That being said, I'm not sure I get the cost justification to jump to 8.6 BLK from any other standard center fire round available in the AR10 or Rem 700 (or similar bolt action)-- especially since the market is almost saturated with choices: .308, 6.5CM, etc. Could it out perform these other cartridges in one way or another? Sure. But how much more is each round going to cost for the first few years of onboarding (or indefinitely)? Further, the AR10 seems to be a little more niche than the AR15.

If it catches on like the 300 BLK did after a few years, I may reconsider, but right now I have my doubts about the cost to benefit ratio.
especially since we already have a 338Fed. The fast Spin thing is what it has going for it, it that is really a thing or not. I guess that is the question.
 

·
Registered
Joined
·
231 Posts
especially since we already have a 338Fed. The fast Spin thing is what it has going for it, it that is really a thing or not. I guess that is the question.
I'm not a ballistics expert, but it is my understanding that a 1:3 barrel twist is read as 1 full twist for every 3" of rifling and that there is an optimal twist for a given range of bullet weights and barrel length (please see What is Rifle Twist | Cheaper Than Dirt for more information). Over the years the AR15 went from a 1:12 to a 1:7 as bullets got heavier and barrels got shorter. I've also been told/read that a certain number of rotations is desirable/necessary for proper stabilization in a certain barrel length.

I would hope that Kevin Brittingham knows what he is talking about since he brought the 300 Blackout to market (Please see video at 8.6 Blackout: Your Questions Answered - Faxon Firearms ), but I personally also would not be an early adopter without seeing some test data. Based on how I understood the video, the 8.6 is being geared toward shorter barrels than you would have on your typical hunting rifle and heavier subsonic loads than are common with 300 BLK.
 

·
Administrator
Joined
·
17,493 Posts
I can't possibly u der stand the point. Only 20 other proven choices to hunt with. Subsonic AR10... Why? Why in the world would you have a sub AR10 with heavy ammo? It kills stuff... No kidding, bullets kill stuff.... But why would you adopt this odd ball... And in the large frame, you 6.5 CM, and even a 6.8 western if you need new toy. Goofing off wand stuffing a fat bullet in a AR15... OK. But an AR10... Makes no sense.
 
  • Like
Reactions: YosemiteCedar

·
Registered
Joined
·
20,051 Posts
Discussion Starter · #8 · (Edited)
I think the point is to dump some of the Kinetic Energy into the spin so it can stay subsonic while hitting harder than another subsonic of equal weight. Strikes me that we've long heard that overspending a bullet hurts accuracy, and this is ridiculously over-spun. It probably needs a 1 in 12" twist to stabilize. It strikes me as a gimmick that will be hard on barrels and perform on par with the 350legend but require a much more expensive framework. I like weird stuff like this, so sort of hoping to be proven wrong. Seems like a 458 bullet would be the better choice. Eta, would that just be a 450 marlin?
 

·
Administrator
Joined
·
17,493 Posts
I think the point is to dump some of the Kinetic Energy into the spin so it can stay subsonic while hitting harder than another subsonic of equal weight. Strikes me that we've long heard that overspending a bullet hurts accuracy, and this is ridiculously over-spun. It probably needs a 1 in 12" twist to stabilize. It strikes me as a gimmick that will be hard on barrels and perform on par with the 350legend but require a much more expensive framework. I like weird stuff like this, so sort of hoping to be proven wrong. Seems like a 458 bullet would be the better choice. Eta, would that just be a 450 marlin?
You could be right, but I can't imagine spin is going to add anything meaningful to energy. It's cool for an odd ball. It's certainly that.
 

·
Registered
Joined
·
20,051 Posts
Discussion Starter · #10 ·
You could be right, but I can't imagine spin is going to add anything meaningful to energy. It's cool for an odd ball. It's certainly that.
that is the question. I can see how it might (especially if the bullet gets decent petals when expanding) , but I just don't know. https://brassfetcher.com/Wounding Theories/Bullet SpinZZZ.html suggest it will do something. I scrolled to the end, it says about 5% comes from the rotation in a pistol, so a round optimized for it might be a 10% boost? stepping up in size would be better. To me, it is more of a science experiment. I'm not sure about bringing a science experiment to market.
 

·
Registered
Joined
·
231 Posts
I can get wanting a larger subsonic bullet than 300 BLK in theory, but due to trajectory (based on my experience with 300 BLK admittedly) I have to question the maximum realistic range of a given subsonic load.

I've read on ARFCOM that short barrels can sometimes benefit from a higher twist rate to provide stability for a bullet-- I don't know how true that is in of itself, but on Q's Honey Badger (offered in 300 BLK as either a SBR or a Pistol) I believe that a 1:5 twist is used in a 7" barrel, whereas, a typical 300 Blackout barrel uses 1:8 twist or less commonly a 1:7 twist.

If I also read between the lines of what Kevin was saying in the above linked video correctly, he seems to imply that the round should work well in a shorter barrel compared to what you would typically use for a similarly powered cartridge. This is where my disconnect is. Why would you really want to go down to 12.5" barrel? A 16.5" barrel seems pretty maneuverable to me for any reasonable use case for a 308 and even then Keltec and IWI both make 308 bullpups that are very compact with decent ballistics (with less paperwork) and you can get a 338 Federal in a 16".
 

·
Registered
Joined
·
20,051 Posts
Discussion Starter · #12 ·
I can get wanting a larger subsonic bullet than 300 BLK in theory, but due to trajectory (based on my experience with 300 BLK admittedly) I have to question the maximum realistic range of a given subsonic load.

I've read on ARFCOM that short barrels can sometimes benefit from a higher twist rate to provide stability for a bullet-- I don't know how true that is in of itself, but on Q's Honey Badger (offered in 300 BLK as either a SBR or a Pistol) I believe that a 1:5 twist is used in a 7" barrel, whereas, a typical 300 Blackout barrel uses 1:8 twist or less commonly a 1:7 twist.

If I also read between the lines of what Kevin was saying in the above linked video correctly, he seems to imply that the round should work well in a shorter barrel compared to what you would typically use for a similarly powered cartridge. This is where my disconnect is. Why would you really want to go down to 12.5" barrel? A 16.5" barrel seems pretty maneuverable to me for any reasonable use case for a 308 and even then Keltec and IWI both make 308 bullpups that are very compact with decent ballistics (with less paperwork) and you can get a 338 Federal in a 16".
A couple things on the short barrel; it is so you have something usable when you slap a huge suppressor on the end of it. A longer barrel is also not needed if you are only hoping for 1050 fps.

Like I said above, the real thing would seem to be the super fast twist imparting more energy on target without breaking the sound barrier.

If the goal is just to toss a big chunk of steel down the barrel, the 45 raptor is just a 460sw made to fit in an AR10. I saw some threads about a 535gr. bullet for the 460sw somewhere...
 

·
Registered
Joined
·
231 Posts
Most of the .308/6.5/.30-06 hunting rifles I've seen have a 20"-26" barrel (maybe I'm old school), so a 16" barrel regardless of the accessories used seems pretty compact to me.

In terms of the twist rate, I think you're more or less on point...

Per The Truth About The Effects of Twist Rate and Gun Barrel Length - The Truth About Guns:
Folks shooting very heavy subsonic rifle projectiles — like the subsonic loads for the .300 Blackout — need to get a fast twist to stabilize those long bullets, but they may have an additional reason to get the rotation even faster than is required for stable flight. Some companies make copper rounds designed specifically to open up at subsonic velocities. These companies, like Discrete Ballistics, suggest that an extremely fast twist rate, like 1:5, helps to allow the projectile to fully open and then cut through tissue like a propeller.
So if a faster twist rate helps to stabilize a bullet, why aren’t all barrels made with the fastest twist rate possible? Well, for a few reasons.
The faster the twist rate the more resistance on the bullet. That just makes sense; as the bore is more perpendicular to the lands, there’s more resistance as the bullet travels the length of the barrel. This slows the bullet down a little, which has a slight negative effect not only on energy delivered, but predictability at long range. It also leads to slightly increased recoil and a slightly shorter barrel life. But again, only slightly.
There is also the possibility of bullets literally flying apart in flight. This is only a concern with fast spin rates on light, thin jacketed rounds moving extremely fast, like we see with the .22-250 Remington and other similar varmint calibers using varmint bullets.
A twist that is too fast may also have a negative effect on long-term precision as well, although not as much as too slow a twist. The long-held belief is that if a bullet is spinning too fast, then the bullet’s nose won’t tip down after the apex of its curve on the way to the target. This nose-up attitude creates increased drag.
This is technically true, but the amount of additional drag on a small arms bullet is so minute that even in the realm of precision shooting, where the tiniest variables count, this one really doesn’t.
The real issue is that a faster twist rate causes an increased dispersion. In this case, we can think of dispersion as group size. Bullets are imperfect things. As they aren’t truly perfectly balanced around their axis, the faster it twists, the more dispersion (bigger group size) will result.
The TDLR paraphrase of the quote: Certain subsonic bullet designs require faster twist rates to have proper expansion and wound cavity creation. Imparting too fast of a twist rate on a bullet increases resistance within the barrel, light bullets can break apart in flight, and can increase group sizes.
 
1 - 13 of 13 Posts
Top