Range Report What twist for my 243 Varmint

[ARCOREY]

I think I'm going to have my 243 SPS varmint rebarreled this year and can't settle on a twist rate. I am currently shooting 70gr. Nosler BT's at 3450 in the factory 1-9 1/8" twist 26" barrel and getting awesome performance on chucks. I would like to be able to shoot a range of bullets from the 70gr. Nosler to the 95gr. Berger for mostly groundhog hunting and some paper shooting to about 600yds. I'm really interested in the Berger 87gr. hunting VLD and the 87gr. V-max for a little more wind resistance. I'd like to go Bartlein stainless Remington Varmint contour finished at 26"-27". What twist are you guys using in this range of bullets? I was thinking 8.5" or 9" but wasn't sure if I was on the right track. Current accuracy is so-so with the factory barrel, not sure if it is due to twist/load or barrel quality.

 

[JCH]

Re: What twist for my 243 Varmint

If you don't want to go above 95grain bullets, the 9 twist will be fine. It should allow you to go up to 105's and still be fine.

 

[Graham]

Re: What twist for my 243 Varmint

It's not the weight of the bullet that matters, it's the length and bearing surface.

 

[WDL]

Re: What twist for my 243 Varmint

I don't think you would have a problem up to 95 grain bullets with a 10 twist.
I have a 10 twist 22" 243 wssm that handles 95 NBTs just fine.

Graham is correct about bullet length and bearing surface.

 

[Graham]

Re: What twist for my 243 Varmint

You probably <span style="font-style: italic">will</span> have trouble with a 10-twist .243 and 95grain bullets.

 

[Bugholes]

Re: What twist for my 243 Varmint

when you rebarrel and get better accuracy, your effective range will probably change. Sooner or later you will be looking at the higher BC bulllets to run in the wind better. I would look at a 9tw or faster. That would enable you to at least shoot the 105 amax (which is pretty impressive on critters large and small)

 

[ARCOREY]

Re: What twist for my 243 Varmint

I know the heavier bullets would do better in the wind, but I would like to keep the bullet weights down to prevent over penetration on the groundhogs. The V-maxes up to 87gr. are very frangable as are the 70gr. and 80gr. NBT's. I don't get pass throughs at ranges as close as 50yds with th 70gr. NBT's. Even though I'm very picky about shot selection and background, the area I shoot is rolling hills and dotted with little farms and roads. I am trying to prevent bullet skip if possible. I put the 95gr. top end for paper punching and the rare event I decide to drag this tank of a rifle out to shoot a deer with it, which will probably never happen. I figure the bearing surface of the new 87gr. Berger VLD will be close to the 95gr. ballistic tips also. Sounds like 1-9" is where I need to be. Thanks guys.

 

[chooter]

Re: What twist for my 243 Varmint

Use this to check what twist rate will work.
http://www.jbmballistics.com/ballistics/calculators/calculators.shtml

 

[Tunanut]

Re: What twist for my 243 Varmint

This guy knows what he's talking about. My 10 twist shoots 85s, 87s, and 90's under half inch @ 100. 95's best groups are just over an inch, 105's run about 4" groups no matter how fast I send them. The 90's are running 3250 fps, 3327 fps for the 85's. I never ran the 87 through the chrono, but I'm sure there around 3300.

 

[ARCOREY]

Re: What twist for my 243 Varmint

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: chooter</div><div class="ubbcode-body">Use this to check what twist rate will work.
http://www.jbmballistics.com/ballistics/calculators/calculators.shtml </div></div>

Great link, thanks for posting that. I ran the numbers and it looks like a 9" twist will stabilize the 80-87gr weights with a MV around 3300fps and the 95gr. NBT around 2900.

 

[jhedg]

Re: What twist for my 243 Varmint

I agree my 243AI 1/10 will shoot the crap out of 75gr Hornady. I have killed groundhogs out to 800yds with it, but 95's are a no go!! 3" groups. If I did it over I would do 1/7 shoot heavy. Drop is drop, but that pesky wind switcharooo thingie. I would like to take more of the variables out
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Graham</div><div class="ubbcode-body">You probably <span style="font-style: italic">will</span> have trouble with a 10-twist .243 and 95grain bullets. </div></div>

 

[Fred_C_Dobbs]

Re: What twist for my 243 Varmint

My .243 WSSM is a 1:10. It will not consistently stabilize a long, skinny 95-gr SMK but will stabilize a short, blunt 100-gr Nosler Partition.

The SMK is about 0.03" longer than the 95-gr Berger but the Miller formula says a 1:10 will barely break 1.0 with it, which is stable but just barely. Litz and others recommend a minimum Miller score of 1.4 which, with the 95-gr Berger, would require a twist of 1:8.8 @3000 fps MV.

 

[darrenk75b]

Re: What twist for my 243 Varmint

Personally I like to twist for potential use, both current and future. I don't want a too-slow twist to hamper me down the road. I'd go 1:8 or 1:7.5 and not look back. Shooting the smaller bullets should be of no concern either.

 

[Fred_C_Dobbs]

Re: What twist for my 243 Varmint

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: darrenk75b</div><div class="ubbcode-body">Personally I like to twist for potential use, both current and future. I don't want a too-slow twist to hamper me down the road. I'd go 1:8 or 1:7.5 and not look back. Shooting the smaller bullets should be of no concern either. </div></div>
When I rebarrel my WSSM, it will be in 1:8.

 

[gregsjt]

Re: What twist for my 243 Varmint

10 twist will work fine for the 87gr vmax. For anything bigger I would go with a 9 or faster.

 

[Tunanut]

Re: What twist for my 243 Varmint

When I rebarrel my 243ai it will be an 8. My 10 throws up to 90g very well. Beyond that, not very good