6.5x284 Norma Build Barrel Twist?!

[Lobber]

Hello All,
I'm preparing for a new build that will be chambered in 6.5x284 Norma with a long Deviant action. My question is regarding barrel twist. It looks like I should be able to get the particular barrel that I am interested in using in either a 1:8 or 1:7 twist (either a 22" or 24" barrel). I will be shooting some of the long VLD-style 140/142 grain bullets, but am also intrigued by some of the heavier 150-155 gr offerings that are starting to show up on the market, especially in a 6.5x284...

It is my understanding that it would be unlikely that the 1:7 twist would "over-stabilize" these long bullets in the 140-155 grain range. However, I am a little concerned that the tighter twist may result in shorter barrel life with a cartridge already somewhat notorious for burning barrels a bit.

Thanks for your help, and I look forward to the discussion.

 

[Rhett Crider]

Hello All,
I'm preparing for a new build that will be chambered in 6.5x284 Norma with a long Deviant action. My question is regarding barrel twist. It looks like I should be able to get the particular barrel that I am interested in using in either a 1:8 or 1:7 twist (either a 22" or 24" barrel). I will be shooting some of the long VLD-style 140/142 grain bullets, but am also intrigued by some of the heavier 150-155 gr offerings that are starting to show up on the market, especially in a 6.5x284...

It is my understanding that it would be unlikely that the 1:7 twist would "over-stabilize" these long bullets in the 140-155 grain range. However, I am a little concerned that the tighter twist may result in shorter barrel life with a cartridge already somewhat notorious for burning barrels a bit.

Thanks for your help, and I look forward to the discussion.

5R 8 twist stabilizes 143 ELDX from 50'-7000' in my 264WM just fine @ 3020MV. Should be all you need however, PAC-NOR does make a 5R-7 1/2.

 

[Lobber]

Thanks Rhett, That's good to know. I'm not too worried about an 8-twist stabilizing the 140-143gr class of bullets, but I'm uncertain if an 8-twist adequately stabilize the 150 gr class of bullets as they seem to add quite a bit of length over the 140-143 grainers, if I try to take that plunge...

I'm wondering if a 7-twist may be adequate for all the above, but I have no idea how that tighter twist might impact barrel life... Perhaps a 7.5-twist may just be the sweet spot for any of the heavier bullets, but the barrel that I had planned on using is not actually available in a 7.5-twist, as far as I can tell.

 

[stwcattle]

I'm sticking with 1:8 in my 6.5x284. I'm in no way convinced the heavier bullets are going to benefit a 6.5x284.

 

[Lobber]

I'm sticking with 1:8 in my 6.5x284. I'm in no way convinced the heavier bullets are going to benefit a 6.5x284.

Thank you for your reply Stwcattle. Would you care to expand on this? I'm interested to hear your perspective on this. Up front the 150's look like a good fit for this caliber to me, but perhaps there isn't enough of a benefit over the 140-143gr bullets to even worry about the 150s.. Thanks!

 

[Rhett Crider]

Thank you for your reply Stwcattle. Would you care to expand on this? I'm interested to hear your perspective on this. Up front the 150's look like a good fit for this caliber to me, but perhaps there isn't enough of a benefit over the 140-143gr bullets to even worry about the 150s.. Thanks!

It's all about your intentions. Hunting or target. And elevation etc..

 

[Lobber]

That's a good point, Rhett. This rifle will be intended for both target and hunting, but I will primarily develop loads for the intention of hunting for western big game species, primarily from 3,500' to 12,000' elevation.

 

[jpfrog]

I have a 26" Criterion Remage barrel coming to me from NSS in 6.5-284 with a 1-7.5" twist. I bought it because I wanted to go with 147 ELD-M and maybe the 150class Bergers if they become available soon.

Also, since it's more of a hunting rifle, I'm going to try @RockyMtnMT Hammers in it. I need to see if he thinks the heavier bullets will work or if I should stick with the 124 hammer hunters.

Barrel should be arriving soon, so no report on how it handles things yet but I'll let you know.

 

[stwcattle]

I'm likely to stick with the speed of the 140's over BC of the 150 class bullets in a hunting application. Testing will tell us where the benefit of the heavier bullets will benefit the 6.5x284, but I'm expecting that benefit will come after 700 yards and i don't hunt past that range.
I have heard Bob Beck has been testing the new Berger 155 bullet with a 6.5x284 and rumor has it its working so lets wait and see.
The 155 should be a nice fit for rifles like the 26 Nosler.

 

[Wedgy]

Being in a non lead state I go for the faster twist barrels, plus you never know what new powder may come along and allow that 155 grain to really fly in a 6.5x284. For example nobody thought a 6.5 Creed could push a 140 close to 3,000fps but RL26 made that happen. Nice to have the faster twist if you can use it.

 

[Lobber]

Man, this has already been a fun discussion! Thanks for all the input so far!

So, not to get too hypothetical here, but do y'all think there would be much of a disadvantage with going with a 1:7 over a 1:8 twist with the expectation of shooting 140-155 grain bullets and/or the long copper bullets, with no intention to go lighter than 140?

To me, it would seem that the 140s would be unlikely to spin too fast to cause many issues, yet could still handle 155+ gr bullets, if one decided to give them a try. That is if one could figure out the appropriate freebore and all.

I don't have much to back that statement, but I'd love to hear what you guys think about that concept.

 

[sable tireur]

Here is a little something more for your consideration.

I took my information and plugged it into the Berger Stability calculator just for grins. I don't always hold by what this piece of math generates but I can report the following:

The 155 in the 6.5x284 Norma running at 2,900 fps at the muzzle will be just slightly less than optimum stability at sea level. But move up to the 3,500 ft elevation you mention and it becomes 'very stable'. This is with the 1:8" twist rate. To gain optimum at sea level the calculator suggests a 1:7.75" twist rate

The 6.5x284 should not be saddled with any complaints about being a 'barrel burner'. Poor powder choice, too long of a shot string, poor cleaning habits, etc. all contribute to a belittling of the cartridge. Choose a cool burning powder without sacrificing velocity and you get longer barrel life. Barrels are an expendable commodity whether you choose to acknowledge it or not. Shoot them and enjoy all the experiences or put it away in the safe and enjoy the longer barrel life...

Regards.

 

[stwcattle]

I do think the Berger calculator pretty accurate.

When I built my 300NM, the internet said 1:8 and a few people thinking 1:7.5 to handle the 230's. I felt this thinking likely BS so I called Berger to get their thoughts. They told me to run a 1:10 like I had planned.

My rifle with a 26'' 1:10 Bartlien shoots the 230's sub .5moa as well as 210's sub .5moa

 

[Lobber]

Sable, your findings from the calculator are very interesting, and somewhat surprising. Thank you for sharing.

Also, well said on barrel life. I completely agree the 6.5x284 seems to get an exaggerated reputation as a barrel burner, especially when proper care is taken as you described. While the barrels are indeed an expendable commodity, they are also quite expensive to replace, particularly with a 700 platform. I will say that I do like to be able to enjoy shooting as many rounds as possible through my rifles before needing a new barrel. Very funny comment about long barrel life through storage in a safe, haha!