twist for 6.5mm 140gn bullet

[Bullshop]

OK I got ahold of Norm Johnson for a rebore on my 6mm/06. Think I am going to a 6.5/06 Ackley. My question is will a 1/10" twist or slower handle up to 140gn bullets?
I know most other chamberings in this caliber are faster twist but they are also intended for longer bullets. I will not shoot heavier than a 140gn and maybe less than that. I want to be able to get all the speed possible so looking for the absolute minimum twist for the 140gn bullet.

[David2011]

The Model 96 Swedish Mauser had a twist of 8.5:1 and as a reputation for shooting the long 139/140 grain round nosed bullets very well. I built a 6.5x55 on a Yugoslavian 24/47 action, rebarreled with a 9" twist that shoots tiny groups with 120 grain bullets but I can't get the speed up enough on 142 grain Match Kings to shoot nearly as well. Groups open up to around an inch- not bad but much larger than the .324" group with 120s. The 142 grain SMK isn't that much longer than a 140. I have been wanting to try Sierra 140s to see if they work any better but haven't been able to get any lately. If I try to increase the velocity the bolt gets stiff and primer pockets start loosening. The chamber is very tight so I feel like I've reached maximum velocity. Hope this helps a little.

David

[Wolfer]

I can't post a link from an I pad but earlier I googled twist rate calculator and got a generator where you put in the length, caliber and velocity and it would spit out the twist required.

You would have to know the length of the bullet in question. Woody

[johnson1942]

the noseler bullet company posted that their 6.5/06 ackley 140 grain bullet needs a 1/9 twist to shoot in. recommended several powders and the ft. per sec was between 2700 to 2900 ft per sec.

[swheeler]

Dan I think with a 1;10 twist you'll be right on the ragged edge, but with the longer barrel and the extra velocity of AI you should be fine. I just measured a 140 Nosler partition at 1.290 the twist calculator I use shows it will be stable at 2800 fps but at 2700 they recommend a 1;9.8. My 264 has a 1:8 twist and I can push that bullet to 3100 out of the mod 70 24" barrel, brothers 6.5-06 I put a 1:9 tist on it 24" he can get the 140 Sierra to 2900+ both are accurate rifles.

[Bullshop]

Anyone tried the Sierra 107gn match king?

[Larry Gibson]

I had a 6.5 - 280 (very close to he 6.5-06 AI in case capacity) for years and shot the throat out, set it back and rechambered and finally shot the barrel out all together. It had a Star 26" 1/10" twist barrel. It handled Hornady, Sierra, and Speer 140 gr FB and BTs well only if pushed to the max. The 120 Sierra and 129 gr Hornady SP bullets shot excellently in it though and the barrel was shot out mostly with those. I suggest the 1/9 twist if 140s are your bullet weight of choice.

I have shot the Sierra 107 gr MKs in my 6.5 Swede and my 6.5-308 (9" twist).

Larry Gibson

[nekshot]

35 tears ago I had rem 700 rebarreled with heavy 26" tube for bench rest with a 9 and half twist and that did well. I would prefer less than 10 if you can get it but would not sweat the 10 inch twist. 6.5 has alot of good bullets to suit any reasonable twist available. Just my thoughts, and yes mine is a 6.5x06!

[Bullshop]

Just as it was in 6mm/06 this rifle in 6.5/06 Imp. is for hunting coyotes period. I am absolutely not set on a 140 gn bullet. What I want is a bullet with a good BC at the highest velocity attainable with the chambering at an acceptable accuracy level. BC does not trump all in trajectory and wind drift. There are times when the lower BC of a lighter weight bullet will give superior ballistics due to the higher attainable velocity over the heavier bullet with higher BC. The Sierra 107 gn match king is a case in point.
This gun is for late winter coyote shooting when most shots are on the far side of 500 yards and sometimes way on the far side.
I talked to Norm and he said he could supply about any twist I want. Mayhaps a 1/9.5 is the best compromise.

[lefty o]

just how much speed are you looking for? a slightly faster twist rate is at most only going to cost you a couple FPS, but it will have a better chance of stabilizing any bullet you choose. you might in the end find you want a heavier bullet so that you can see bullet impacts when you miss. in a 6.5-06 the slowest i would consider is a 1-9".

[Larry Gibson]

Bullshop

Mine 6.5-280 was built many years ago as a long range rock chuck and coyote rifle. Back before they had all the high BC bullets we have today. Bullet of choice back then was the Hornady 129 gr (pre InterLoc) and it worked very well out to 800 - 100 yards. These days I would use the 120 gr Nosler ballistic tip though so the 10" twist would work just fine. The Sierra 120 SP would be my second choice.....both are quite deadly on coyote at some pretty extreme ranges. I pushed both well past 3200 fps (had a chronograph in '74) with accuracy at 200 yards of 1" and sometimes less for 5 shots. My hits at long range improved greatly when I went from standard cross hair using hold over/hold off to a 10X with Lee dots added for hold over to the 1st Weaver T-16 that came into the NW. Being able to adjust accurately for ellevation and windage made all the difference in the world. Got so I wouldn't shoot a rock chuck less than 300 yards away and most often less than 500 yards. Took 2 rock chucks in 3 shots at just over 800 yards. Made a couple at 1000+ a couple times. Of course coyote are fair game at any range.......

Larry Gibson

[Bullshop]

Thanks Larry! Those are the bullet weights I had in mind.

[johnson1942]

sounds like a quite a gun your building. 800 and 1000 yard shots are really in the expert range and with a good cal of a gun and the shooter behind it, WOW.

[Bullshop]

The gun has already been built and has been in service. It is shot out so is going to be rebored to keep it in service. It has served well for such shooting. My standard coyote load pushes an 85gn bullet to an average MV of 3777 fps. That is fast and is why it now need a rebore.

[Dutchman]

The Model 96 Swedish Mauser had a twist of 8.5:1

pssst.... m/94, m/96 & m/38 = 1:200mm = 7.87"

Carl Gustaf m/63 & m/80 target rifles = 1:220 = 8.66"

Dutch

[Bullshop]

pssst.... m/94, m/96 & m/38 = 1:200mm = 7.87"

Carl Gustaf m/63 & m/80 target rifles = 1:220 = 8.66"

Dutch
But for what bullet style/weight
I wont be shooting those.

[Love Life]

You're going to have to juice it hard if you want to run those bullets. I'd go with a bit of a faster twist.

[Bullshop]

No I am convinced that the 1/10" twist will do what I want with the bullets I want. I think I can make the Sierra 107 VLD match king go very fast with the long barrel and slow twist. It should handle bullets in the 120gn range and a bit over just as well.
I will have no need for bullets over 130gn. I have a bunch of 258" 120gn bullets I may try to bump up to .264". A single .264" point form swage die should do that.
If you consider that the 258 caliber does quite well with 120gn BTSP bullets with a 1/10" twist then a slight jump up in caliber should do equally well or better with bullets of the same length.
A 120gn bullet at .264" should be shorter than a 120gn bullet in 258" all else being equal so should be better stabilized.

[nekshot]

bullshop I see no regret in that twist for your application as a fur getter.

[B R Shooter]

I have shot 9, 8.5 and 8 twists in the 6.5. I even shot the 6.5/06AI in 1000 yard competition. You can push bullets pretty fast with that round, and with an 8 twist, you can actually spin a bullet apart if the jacket is too thin. Berger actually made thicker jackets to stop this from happening. With 140VLD, a 9 may be borderline, although mine stabilized OK. I would go 8.5 and you will be covered on anything you put in it.

[swheeler]

Dan I think you will be just fine with the 10" twist and the bullets you want to shoot, GO FOR IT!;) I wish my 264 mag had a 9 or 10 twist instead of the 1:8.

[300blk]

If you don't mind the price the 123 Lapua scenars are some of the best in that weight range I have run. The 130 berger vld's are nice but somewhat twist specific.

[DCM]

I would use the twist rate calculator here http://www.bergerbullets.com/litz/TwistRuleAltWP.php

Edit : or one of the ones here http://castboolits.gunloads.com/showthread.php?107867-What-twist-rate

[300savage]

i know that you did not ask but when i was looking for the same kind of rifle for that situation i finally figured with all considered i could not beat a 25_06.