Best 6.5 Creedmoor twist rate?

[Litehiker]

The Ruger American Predator in 6.5 Creedmoor that I've ordered has a 1:8" twist rate.

Berger's online calculator says that rate is good from 120 gr. through 140 gr. EXCEPT their Hybrid Match, a very long bullet, which would likely need a faster rate.

Anyone have a "better", wider weight range twist rate on their 6.54 Creedmoor rifle?

 

[trickytune]

I think you will be fine with the 140g hybrid. I looked at the calculator and they have updated it. The length listed for the hybrid is longer than the one I have in a spreadsheet from them slightly. At 20oC and zero altitude @ 2650 fps I get 1.52 SG which says comfortable. I think Brian stated they are stable from a accuracy viewpoint above 1.23 SG and to obtain full BC aim for 1.5 or higher.

I hope thats the case I have some waiting to load for my 260 rem 1:8"

 

[BergerBoy]

The Ruger American Predator in 6.5 Creedmoor that I've ordered has a 1:8" twist rate.

Berger's online calculator says that rate is good from 120 gr. through 140 gr. EXCEPT their Hybrid Match, a very long bullet, which would likely need a faster rate.

Anyone have a "better", wider weight range twist rate on their 6.54 Creedmoor rifle?

I am building one with a 7.5 twist. I like have my SG numbers a bit higher than most. You can't over stabilize a bullet.

 

[338 bruce]

savage preditor max1 6.5 creedmoor, 140 amax shoot very good 2865 fps, 95 vmax become unstable if pushed faster than 3250 fps.

 

[Litehiker]

OK, looks like 1:8 is fine up through 140 gr. so I went ahead and got the Ruger American Predator. The price, decent trigger and the American rifles' reputation for accuracy were big factors in that choice. Yeah, a tactical Tikka may have been better but I didn't want to lay out that much money initially.

I'm getting a muzzle brake for its 5/8" - 24 t.p.i. factory threading. It will be timed by my gunsmith (Bentwood in Henderson, NV) so it screws on with a closed bottom that mitigates blown dust.

This is a "starter" rifle so I can try long range competition and see how I like it.
I'm putting a 20 moa rail on it with a Badger Ordinance flat, integral (one piece) 34 mm. scope mount.

I'll use my Bushnell ERS 3.5 - 21 scope with the Horus H59 reticle. That scope and base will travel to any better rifle I get if I stay in the LR competition game.

 

[Litehiker]

UPDATE:
I'm thinking of selling my Ruger American Predator, accurate as it is, and buying a Browning X-Bolt.
BUT... this year 6.5 CM X-Bolts have a 1:7 twist rate!
I called Browning and asked that would be too fast for a 120 gr. bullet ands told by a tech that "It depends if your rifle likes it or not." That is a cop-out answer B/C in the AVERAGE rifle and AVERAGE 120 gr. load IMHO it is likely too fast.

So, where do I go, besides some opinion forum like Sniper's Hide or here, to get a ballistician's or ammo maker's opinion on this?

Eric B.

 

[Greyfox]

I'm neither a Ballistician or bullet maker but this is my understanding/viewpoint on the subject of twist rate. Everyone seems to jumping on the "fast twist" bandwagon these days choosing the fastest twist available without regard for the optimimum load that will be used in the rifle. Yes, a fast enough twist must be used to stabilize your chosen bullet and velocity, but the rationale that more is better in all cases may have consequences.. While it may be true that you can't over stabilize a bullet, there are other factors to consider. Accuracy, barrel life, and ES, and velocity. The simple physics is that the bullet has to be grabbed by the rifling at the throat. The faster the twist, the more time and distance is necessary for the bullet to "grab' the rifling, a difficult task if accelerating from 0 to 3000FPS in nanoseconds. Sliding and torsional forces prior to grip can effect its stable entry into the rifling and cause accuracy degradation and premature wear where the rifling meets the throat. Also, a faster twist generally results in lower velocity for a given set of conditions. This is the reason Benchresters choose the slowest twist possible that stabilizes with their chosen load. This IS the reason the premium barrel makers supply their barrels in a wide variety of twist rates. It's also true that many shooters(and possibly some rifle makers) may never realize a difference due to lower(or the absence of) performance standards. .

 

[th82457]

I think Greyfox is spot-on. In addition, I believe the faster the twist rate with a given load you will not only lose some velocity - but also increase chamber pressure at the same time - probably not your desired result.

 

[RockyMtnMT]

I think Greyfox is correct. From my perspective as a lead free pure copper bullet maker faster twist rates are needed to shoot the heavier bullets. The copper bullet is longer for the same weight as a lead core bullet, thus requiring more twist to stabilize. As a general rule the pure copper bullets are not as fragile as the jacketed bullets so there is less chance of the force of starting the bullet into the twist, in that moment of initial acceleration, causing damage to the bullet. Seems today's cup and core bullets have improved to take the higher vel and faster twist rates that are available now that were not too common even 10 years ago. If you decide to shoot lighter for caliber bullets you should not have trouble unless they are not well built. You could find yourself slightly limited in your options for light bullets but have much more options for heavier ones.

Higher rpm's or stability factor does aid in a bullets ability to stay point on and track straight after impact, thus aiding in terminal performance. For me as a hunter this has become very important to me. After all the testing that we have done, the first thing I consider when choosing a bullet is the sg for good terminal performance.

All in all I think there is more upside to the faster twist rate than down side.

Steve

 

[Barrelnut]

I always found this article interesting. Seems Litz has tested this somewhat and velocity change was only about 1.33 FPS per inch of twist increase. I always assumed it would be somewhat higher. Now I wonder how much the pressure would increase with the additional resistance causing the 1.33 FPS loss in speed...
http://bulletin.accurateshooter.com/2016/01/the-effect-of-barrel-twist-rate-on-muzzle-velocities/

 

[Edd]

The difference in the angle of the lands between an 8" and a 7" twist in a 6.5mm barrel is less than 1°.

 

[Lowbank]

UPDATE:
I'm thinking of selling my Ruger American Predator, accurate as it is, and buying a Browning X-Bolt.
BUT... this year 6.5 CM X-Bolts have a 1:7 twist rate!
I called Browning and asked that would be too fast for a 120 gr. bullet ands told by a tech that "It depends if your rifle likes it or not." That is a cop-out answer B/C in the AVERAGE rifle and AVERAGE 120 gr. load IMHO it is likely too fast.

So, where do I go, besides some opinion forum like Sniper's Hide or here, to get a ballistician's or ammo maker's opinion on this?

Eric B.

Hi Eric I'm looking at the x-bolt in 6.5 as Well how did you go? Why the X-bolt over the Tikka?

 

[Litehiker]

Lowbank,
I did get the 6.5 CM Browning X-Bolt Pro. BUT I'm selling it B/C I got the exact same rifle (X-Bolt Pro) in 6.5 PRC. That's how much I like the X-Bolt Pro.

It's a better buy in terms of features like factory lapped barrel than the SAKO Carbonlite not just because it has a much lower price (by about $900.) but because it is at least equal in quality to the SAKO Carbonlite and above the Tikka in quality.

But ya know, I'd have kept that very accurate Ruger American Predator IF it had a locking bolt when on safety. Are you even listening Ruger??

Eric B.