243 twist 1in8 or 1in7

[jimbo88mm]

Will be ordering a new barrel soon.

Most shooting is done inside of 500 yards but I would like to give 1000 yards a try sometime down the road. I'm worried that the 1in7 twist is too fast for med weight bullets (87-100gr). While I expect to shoot the heavier bullets (107-115gr) most of the time I would like the flexibility to shoot lighter (and cheaper) stuff when shooting close range (100-300 yards). My thoughts are that the 1in8 is more versatile, as such that's the direction I'm leaning.

What do you guys think?

Thanks

 

[rcw3]

I would go with a 7.5" twist if you are going to shoot various 115's. Stay away from a 7" twist as that can be a problem twist for a 6mm, that extra little bit of twist will typically cause pressures to spike - been there, done that with a couple barrels - won't ever get another 7" twist 6mm.

Robert Whitley

 

[jimbo88mm]

Thanks Robert, That is good to know regarding the pressure issue.

 

[15Tango]

I stabilize 105 VLDs out of a 9 twist very well. My guess is a 8 is all that's needed on 6MM for the 115s, especially with a .243 Win. which can launch them at very respectable speeds, or like Robert said, 7.5 max.

Wayne

 

[Scott Harris]

Krieger recommends 1:7.5 for 115 DTACs. 1:8 is probably perfect for the 105gr

 

[cmillard]

i would go with an 8" twist. i have shot the 115 berger vld out of my 5R .236 bore 8" twist krieger 6BR with no signs of wobble, even at 350 yards. you will do just fine with the 8".

 

[kristian55]

Will be ordering a new barrel soon.

Most shooting is done inside of 500 yards but I would like to give 1000 yards a try sometime down the road. I'm worried that the 1in7 twist is too fast for med weight bullets (87-100gr). While I expect to shoot the heavier bullets (107-115gr) most of the time I would like the flexibility to shoot lighter (and cheaper) stuff when shooting close range (100-300 yards). My thoughts are that the 1in8 is more versatile, as such that's the direction I'm leaning.

What do you guys think?

Thanks

OK.
It is necessary to take into account length of bullet which you will utillize.
Twist 1:7 more universal-it is possible to utillize more long and heavy bullets, and variant twist 1:8 you will be able to utillize short bullets less weight.
P.S.
Length of bullet can be from 0.8" to 1.26" at twist 1:7.

 

[jghoghunter]

I shoot a standard 243 with a broughton 1/7 twist with no problems. We shoot from 100 yds where it will shoot in the .1's and I have shot 2", 5 shot groups IN PRACTICE (too bad just practice). I have never shot anything lighter so I cannot comment on the light bullets.

 

[Yellow11]

Be specific with your bullet selection, then apply Don Miller's formula to your choice and you will arrive at the correct answer, not an approximation.

Berger 115's need a 7 twist, DTAC 115's are shorter and need 7.5 twist.

I shoot both of these bullets at 1200 yards weekly in a 7 twist, but use a 9 twist for Berger 88's and MK 95's

 

[cmillard]

if i were you, i would go with a 7.5 or a 7.8" twist. since you will be pushing the bullets real fast, you won't need the extra spin. tubb shoots the 115 dtacs just fine out of both 7.5" and 8" twist 6xc. and he doesnt get the velocity that you will get out of a .243. if you go with the berger 115s, be sure to get the target bullet and not the hunting. the target version has a thicker jacket and can take more rotational forces. i would stay away from the 7" twist, but that is my $.02. just read through some of the guns of the week to see what they are shooting.

 

[jimbo88mm]

Thanks for the feedback guys. I've decided to go with a 1in8.