So my old 6.8 system is the SPC II chamber, but uses a 1:10 twist. For my next project I am considering the Noveske freebore chamber with a 1:12 polygonal twist. From my readings, it seems that the SPC II chamber, with a 1:11-1:12 twist, and 4-grooves is the way to go. Anyone have any experience with the new Noveske barrels? Thanks.
Fantastic barrel capable of amazing accuracy.
Their barrels are top notch.
Thanks!
Yes and they are a work of art.
It’s money well spent if you want the best
consistant superb accuracy & their KIT works.
Well I guess that there is a consensus then 
Now I’m just trying to decide if I want to buy the complete upper, or just go for the barrel and piece the rest together for a better budget.
Withdrawn.
They would prefer you not to take it apart it, hence lock-tite.
I have no idea where this keeps coming from. Screws on BUIS and rails are the only areas that get threadlocker.
Internet rumors that just seem to run amock.
It used to be on ADCO’s website for sometime.
I went there to get the link so I could post it and it was gone.
My apologies to Noveske and I will not post it anymore.
Rocksett on the silencer mount flash hiders?
Way back when we were a custom type shop we installed gas blocks without pinning. They got a good dose of red locktite, maybe that was it?
I purchased the Noveske 6.8 12.5" Crusader upper with switchblock. It can easily shoot 1 MOA at 100 yards with the right ammo and I’m not even a good shot.
You won’t be disappointed!
I have three of the Noveske’s in 6.8 SPC. A 7.5" in the old configuration, and a 12.5" and a 16" in the new configuration. Great guns all, you’re going to love it!
There have been some 6.8 barrels that have had various problems of tight chambers and bore dimensions. Those barrels also happened to be 1:10 or faster twist. That does not mean 1:10 twist is a problem in itself, but people associate the two, because that is what is easily observable about the barrel.
The military and our shooting comminity moved from 1:12 to 1:7 for .223/5.56mm with no pressure problems even with NATO M193 ammo, and yet some believe that if you go from 1:11 to 1:10 twist in 6.8mm it causes a problem.
I have seen no evidence of that except for some testing that was done with strain gauges and there were additional variables not pinned down. For example, the barrels differed in other ways. The way to do a test would be to make pressure test barrels for use with conformal transducers. The barrels could be, for example, PacNor 3-groove in 10 and 13 twist and cut with the same chamber reame. Based on what I have heard about both .223 and 308, I would expect at most about a few hundred PSI difference per twist value.
You could also then take the same twist and compare a SAAMI with SPC-II chamber - all else being the same. I would expect at most a 1500 PSI difference.
So in comparing a 1:12 twist SPC-II rifle to an in-spec SAAMI 1:10 twist rifle, more than a 2000 PSI difference would surprise me.
Is that significant? Well better is better, so I would go for an SPC-II chamber. But to put it in perspective, the round has a maximum average pressure of about 58,000 psi and a SAAMI proof round - shot in most SAAMI barrels, is about 78,000 psi.
Strain gages can be ok for comparing loads within the same barrel, but you can’t really compare data from one barrel to another because the gauge location and the thickness of the steel under the gauge is so critical to the result. Further, you can’t even normalize two barrels by firing a calibration round in each if the chambers are different…
One may want to consider faster twists for certain applications:
- Shorter barrels.
- Longer bullets (Some 130s and longer).
- Cold weather.
- Subsonic loads.
- Sound suppressor combined with factors 1-4.
- Increased terminal performance with some projectiles.
A Palma rifle is one thing, but I don’t believe in trying to look for the least amount of stability in a combat rifle. It needs to work with a silencer, at -20 F, and a faster twist may help some bullets perform.
1:10 is not in danger of being too much twist.
In making a barrel I would look for a few things:
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Try to keep headspace at GO+0.002. This will lower pressure and help with feeding. There is generally 0.003 of ‘crush’ built into SAAMI headspace.
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Don’t use a minimum reamer for a semi/full auto. Have the reamer made to minimum + 0.0015 or so.
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Make sure that the bore cross-sectional area is not at or below SAAMI min. Be careful about chrome plating adding thickness.
As you point out later in your post, it does cause a reduction in performance, just not a major one. I think most involved in the debate have come to the conclusion that the biggest difference in the performance between SPC and SPCII is the lengthening of the leade on the chamber with the attendant drop in pressure allowing hotter loads. Certainly I have spoken with HTR in person on the topic and that seemed to be his take on it.
But with that said, there is a reason almost the entire industry has moved away from the 1:10 spec after testing. That rate was really just used because it was compatible with the .270 Winchester. If I remember correctly, Holland and Co were using a 1:11 twist rate for development. I know Noveske spent better than 6 months in testing different combinations of chamber and twist rate before settling on the 1:12 rifling and modified chamber with increased free bore since I was in touch with them at the time.
I personally have a 1:10 Noveske barrel with an SPC chamber that will fire any of the SSA Tac loads. Primers show some signs of flattening with the 110gr Accubonds but not badly. I would expect the lengthening of the leade to make even those go away. OTOH, I see no pressure signs whatsoever with even hotter ammo fired from with either of my Noveske’s with the new configuration of chamber and rifling. I’m currently waiting on a reamer to do the conversion. So while the slower twists appear better, they certainly aren’t the whole story.
Is this hypothesis purely theoretical? Earlier in your post you were dismissing testing because you felt it was flawed but don’t see any testing at all on your part to base your conjecture upon nor am I aware of any qualifications you may have as an expert in the area. Can you provide supporting information I’m not aware of?
Given the differences I see in pressure signs between my Noveske with 1:10 rifling and SPC chamber and the rifles with the newer configuration I would certainly expect to see a greater difference in pressure than 2K.
I said it may raise chamber pressures by up to a few hundred psi over 1:11. That will not reduce the performance of normal (under 60,000 psi) ammo.
I agree with that, but when reading various forums it is clear that people still incorrectly harp on 1:10 twist as something to avoid, but then don’t make it clear that is only with barrels that have other problems.
Agreed the rate happened to be the 270 rate, but that does not mean it is bad for 6.8mm. I already showed how the Miller twist values of 1:7 twist 223/5.56mm happen to correspond to 1:9 twist in 6.8mm with the range of bullets typically used.
1:11 and 1:12 are fine choices also, as is 1:9, depending on the goals.
The chamber and bore also changed, so one cannot isolate twist as the issue.
I dismissed that testing related to twist because there were other uncontrolled variables, not testing in general.
That does not conflict with what I said. You may also have a new bore with a different cross-sectional area and possibly a different chamber reamer. It seems like Noveske did a lot of great things across the board. Someone could also improve 1:10 twist barrels as a package if that was their desire.
I am not saying existing 1:10 barrels are good (nor am I saying they are all bad). I am saying - one could make a new 1:10 or 1:9 barrel with all of the other tricks and have no problems with pressure.
Is the Noveske 6.8 driven by a gas piston? I was wondering what the reliability is compared to an ak-47. If it could have close to the reliability of an ak-47 when firing from a dirty barrel, along with the more knock down power than an ak-47, I might have to add this to my wish list.
Noveske does not sell any factory piston setups, as far as I am aware of. For more info, visit their site at: