6mm 75 - 85 grn bullets what twist

[500YardHog]

Im looking to build a 6mm AI or .243 AI to shoot 75 to 85 grn vamint bullets at 3600 fps of faster and i was wondering what twist i would need.87 grns would be tops but im looking hard at the 75 grn V max it has a good B.C,.330) and i could push it fast.

 

[tightneck]

I'd go with a 10, but I'm biased. I have a krieger 10 twist in 6AI that loves the 75 and 87 V-Max's

 

[500YardHog]

I have read that one and he uses a 1 in 14 but he goes on to say you have to boot the 75s out at close to 3900 to get them to fly right.I'm not sure i want to be held to that velocity to get accuracy out of the 75s.I have seen a few 1 in 10s but 1 in 10 seems like a big bullet twist .I guess its all relevant to the caliber your shooting.Would a 1 in 12 be enough?I'm not interested in anything over 87 grns.

 

[Bobs243Ackley]

I went with a 26" long Pac Nor 12" twist for my new barrel for my .243AI. I went with this twist since I use the cartridge primarily as a varmint rifle, with a secondary capability for light big game back up rifle use. It will handle up to a 87 grain V-Max bullet that the 14" twist would have difficulties with.

Cordially,
Bob Blaine

 

[500YardHog]

I am leaning towards a 1 in 12 .It seems to be the right range for the 75 to 87.

 

[takman]

I am having a 6mm BR being built with a 1-12 as I am looking to use it as a varmint rig using 70-87 grainers. All of my others are larger caliber and I chose this twist over the 1-8 so I would stay away from the larger bullets.

 

[egwyn]

I have a 12 twist. It works real well with a 75 g V-max

 

[oldtime_hunter]

I would lean to the 1-12 for the bullets you mentioned. I dont like the trade off for the heavy bullets

 

[Tommie]

A buddy is shooting 87 VMax bullets in a 1-12" 6XC. Shoots fine, but I wouldn't go with a slower twist that that.

 

[EdwinD]

10 twist is correct answer to question.

 

[chino1969]

I have a .243 A.I. with a 1-10" that does very well with the 87grn. V-Maxes. I just had a 1-12" put together for bullets up to 75grns. The 1-12" rate of twist will stabilize 65's, 68's, 70's, etc. and there are quite a number of really accurate bullets in those weights for varmints. I had another 1-10" barrel put together for the heavier bullets but will keep the 1-12" for the lighter bullets. It still amazes me the length that varmint hunters, myself included, will go to in order to drop varmints.
Chino69

 

[AckleymanII]

The 1-12 will stabalize the 75g V max even in cold temps, but it will take a 1-10 for the 87's. Twist rates do vary some from barrel to barrel and if you were to get a 12 1/2, you may be in real trouble with the 87's especially on a cool day.

Good luck!

 

[500YardHog]

Thanks for the input guys . I ended up ordering a Cooper Phoenix in 243 Win with a 1 in 10 twist .I think I'm going to try and load for the 75 grain V Max first.

 

[StephenPerry]

500 H
You might consider a 1-8 Krieger. I shot one a couple weeks ago at Varmint Silouhette out to 600M. Missed 1 out of 30 at 400, 500,600 M. The 1-8 in a 6 will handle your 80 grn stuff and allow you to move up to 105's.

Stephen Perry
Angeles BR