Having a rifle built on my M70 action and will be shooting 13-140 gr bullets exclusively. I'm thinking of either an 8 or 8.5 twist rate with a 26" tube. Thoughts?

Thanks!

Gary

That should work perfectly.

Thanks, Matt...appreciate it!

Gary

I just did a 6.5-06 in an 8.5 twist. It shoots 140's exceptionally well.

Thanks SS......You're thoughts mimic exactly the consensus I'm hearing. I just don't plan on shooting any 120's or lighter....that's why I have a 25-06.

Appreciate it.

Gary

8.5 should stabilize all bullet weights. I always knee jerk to the faster twist . And would go with 8" twist. Is it going to be an Ackley Improved ? Less brass stretch !

As fast as the 6.5-06 runs, a 1 in 8" twist is unnecessary, but it wouldn't hurt. I have a set of RCBS 6.5-06 Ackley FL dies that I'll sell you cheap if you decide to go that route.

I have my 264WM twist at 1:9", it shoots 140's without drama. If I had had a better idea of how long the Berger bullets were, I might have gone with a 1:8.5", but my rifle still shoots the Bergers quite well.
I don't think the faster 1:8" is necessary for 140's, but it certainly wouldn't hurt.

Cheers.

No, gents, not an improved...straight up 6.5-06. I think the 8.5 is probably the way to go, but the 8 isn't a deal breaker. Berger says 8.4 for 140's and 8.7 for 130's...and I may load some 130's on occasion. Thanks for all the input!

Gary

We went with the 8 twist. It was either that or a 9

Jim

Both of mine are 8 twists and I have never wished I had the slower twist. I shoot mostly 130s - Accubonds and Bergers, but they also shoot 125 Partitions very well. They are very accurate with the 140 Bergers as well, I just like the 130s better because I have a .260 that likes em so I have crapload of them. Either way you'll be fine, but with the 8 you will never have to wonder if you will end up with most of a box of long wobbly bullets.

I had a custom 264Win put together with a Shilen 1/9" twist barrel and it wouldn't stabilize 140 grain bullets. I then bought a custom TC Encore barrel in that cartridge that was 1/8" twist and it would stabilize 160 grain bullets.

Jim, that's perfect. Was leaning that way and much prefer that to the 9 as 130's will be the lightest this rifle sees.
Thanks to all for the responses.

Gary

I want a 6.5-06 too.
1:8" twist would not hurt anything on a hunting rifle, especially if you want to use 160-grainers at close range for big game.
"Over-stabilization" is not a problem there.
Also not a problem with 140-grainers within 500 yards.


The lore is interesting.
Essentially a more sensible form of the 256 Newton forerunner (.256 bore, .264 groove/bullet diameter).

IIRC, Ackley could not improve on the standard 6.5-06 velocities with the powders he had available then for his AI version.

For a hunting rifle, I would go with slicker feeding standard 6.5-06 and live with some case stretching.
Neck up .25-06 brass or neck down 270, 280, or 30-06, whatever works best with the least neck turning/reaming/fuss.

Yep, the 6.5-06 should have been the one chosen, instead of either the .25-06 Rem. or 270 Win.

RIP, I agree. Even getting another 100 fps (AI)isn't worth it to me for this rifle. I'm quite sure with a 26" barrel I can get right about 3000 fps with 140 gr bullets....and that will be just fine.

Thanks!

Gary

quote:

Originally posted by Luckyducker:
I had a custom 264Win put together with a Shilen 1/9" twist barrel and it wouldn't stabilize 140 grain bullets. I then bought a custom TC Encore barrel in that cartridge that was 1/8" twist and it would stabilize 160 grain bullets.

Ditto. Had a 1:9 Shilen on my 6.5-06 and I would not stabilize 140gr target/match bullets like Berger or Sierra. Would stabilize 140gr flat base bullets. When I shot that barrel out, I replaced it with a 1:8 twist in 6.5-06 Ackley, and now have no trouble shooting 140gr bullets of any type.

Barstool(er)

My 6.5-06 was made with a 1:8 Douglas Supreme barrel on a Brno ZKK600 action for 140gr bullets and handles these longish projectiles well.

JBM Ballistics has an on line stability calculator which uses a modern formula. Be sure to enter the lowest temperature at which you intend to shoot. You will need bullet length. JBM has a chart. Why guess? It's quick, easy a free.

Thanks, Brice....I'll check that out.

Gary

I'd do 1:8, don't see a downside.

I specified a 1/8 twist on my 6.5mm SAUM

Thanks, gents. Jim has ordered a 1-8"...that will be perfect. I don't need anything but 140's or maybe 130's going down the pipe....have a 25-06 for the lighter weight bullets. This is going to be my western rifle...along with my 340 Weatherby.
Thanks for all the replies!

Gary