243 rebarrel and twists

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243 rebarrel and twists

Postby tbirdman74 » Wed Sep 10, 2014 4:59 pm

Time has come to rebarrel my trusty old 243. Still shoots decent, but looking down a clean bore, it looks like a haul road in a coal mine. I mean bad. Original barrel is 1-12 or 1-14, have to measure to be sure. Shoots like a laser with the 58 gr vmax. Anything over 80, not so much. Planning on 22-24 inch, what would you guys recommend for a twist to shoot heavier bullets, say even the 107(I think) bergers? Do I need to go 8 twist or wiould a 9 or 10 get me by. And would an 8 twist affect the lighter bullets? I've read hours worth of internet banter on it, and figured I'd ask the guys that rarely steer me wrong.
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Re: 243 rebarrel and twists

Postby 3rdgeargrndrr » Wed Sep 10, 2014 5:35 pm

308 conversion
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Re: 243 rebarrel and twists

Postby wildcatter » Wed Sep 10, 2014 6:53 pm

If you are going to dedicate this to the Heavies only, then a faster twist is in the offing. But yes, that will effect the lighter bullets adversely. So, if you are going to shoot all bullet weights, then the trade off is to stick with the factory twist, simply because, they have already done the trade off figuring.

Good luck..

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Re: 243 rebarrel and twists

Postby tbirdman74 » Wed Sep 10, 2014 7:57 pm

3rdgeargrndrr wrote:308 conversion
Image


Sneaky, sneaky... I've already got the same gun in 308, have considered a light 6.5 creedmoor, but I really like having a 243. Its my "grab and go" gun for most occasions. Wildcatter, what do you think would be an even tradeoff for being able to shoot 105 gr and still be able to run the 58 gr pills? As is, anything over 80 gr it just doesn't shoot worth a damn.
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Re: 243 rebarrel and twists

Postby wildcatter » Thu Sep 11, 2014 12:14 pm

tbirdman74 wrote:
3rdgeargrndrr wrote:308 conversion
Image


Sneaky, sneaky... I've already got the same gun in 308, have considered a light 6.5 creedmoor, but I really like having a 243. Its my "grab and go" gun for most occasions. Wildcatter, what do you think would be an even tradeoff for being able to shoot 105 gr and still be able to run the 58 gr pills? As is, anything over 80 gr it just doesn't shoot worth a damn.


That's a toughie.

See in the 243 most barrels have mission specific twist. As you say laser shots with the 58gr bullets and not so good with the 105gr. It's obvious to me that your rifle was made to shoot Varmints, I mean 58gr bullets are hardly meant for moose. But Moose are in the offing with a 105gr. With such a Hugh spread in bullet weights, you'll have to either use the same twist as you have now, stabilizing the 58's very well, or a much faster twist for the 105's, but then the 58 are going to suffer, if the 105's start to laser, so-to-speak. You could pick a middle of the road twist for the middle ranged bullet weights, but then the true heavies and lighties will suffer somewhat and most of the 75-85 grainers are well suited to moose. Yes, Moose, with a .243! I did a long turn as a PH and have seen Many-Many Moose downed with a .243 and a 22-250, of course bullet selection and shot placement became critical.

So, you're in a bit of a pickle. But defining your mission as to what weight bullets you want, need to shoot, and what you want to shoot, will help allot. In the mean time, measure your twist and get back here and let us know what it is. If you are not sure how to measure twist, Hoot has an excellent method, with a cleaning Mop to do this task..

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Re: 243 rebarrel and twists

Postby pitted bore » Tue Sep 16, 2014 7:05 pm

I've been around and around with the slow and fast twist questions recently, playing with a 244 Rem (1-12"), a 223 (1-12), and a 222 (1-14). They really don't like long bullets.

I've also loaded for some fast-twist barrels, and found that they did just fine with bullets shorter than optimal for their twist rate. They did not produce benchrest match-winning accuracy, but nice groups of less than a half-inch.

Some rather clear reading on the "problem" of over-stabilization can be pursued at this link: 1-12 vs. 1-9 Twist in .223's While the topic is the 223, the generalizations are useful. (Apprropriately for this forum, the word "Bushmaster" is used toward the end of the piece, in which a 1-9 carbine does fine with short bullets.)

Back in the bad old days, bullets were not as well-made as they are currently, and "proper" twist rates were important. A batch of imperfectly balanced bullets would make a much wider group when spinning faster than needed for just enough stability. Now that bullets are better made, it's rare to get a batch that will open up a group if spun even much faster than needed for its length.

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Re: 243 rebarrel and twists

Postby MarkCO » Fri Sep 19, 2014 7:51 am

The "suffering" with light (short) bullets in faster twist barrels is a lot less than the suffering with slow twist and heavies. One of my .243s is 1:9, the other 1:12 and I can' hardly tell the difference between the two when shooting the 65 grain VMax. But when I get to 90 grains and up, I can really see the difference. The 95 grain Ballistic tip is still right about 1.2 MOA in the 1:12 and what my boys and Dad use for Pronghorn. Most of the guys shooting long range competition with the 105-115s are shooting a 1:8, or even a 1:7 with gain twist. With those, they sometimes blow up the 58s and they don't shoot the 60s well but okay with the 70s. Of course, it is a matter of degrees as we are talking about rigs for which anything over 1MOA is "poor" accuracy.

My next .243 barrel is likely going to be a 1:8 gain twist from Bartlein. The gain is a little easier on the the lightweights and will last a little longer as well.
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Re: 243 rebarrel and twists

Postby tbirdman74 » Fri Sep 19, 2014 8:25 am

Mark, how do those gain twist barrels work? I've read a little about them, but not enough to know much. Does, say, an 8 gain start as 8 and gain from there, or start slower and gain to 8?
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Re: 243 rebarrel and twists

Postby MarkCO » Fri Sep 19, 2014 10:32 am

An 8 gain twist typically starts slower and the 8 would be the final number. I've shot them enough to know they offer an extra measure of accuracy and open the window a bit for the usable bullet weights. Bartleins are about $325 to $400 depending on choices, so they are a tad more coin, but they shoot better than some of the other makers that cost more. :)

I am looking at starting 1-12 with a finish of 1:8, probably a 24".
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Re: 243 rebarrel and twists

Postby MarkCO » Fri Sep 19, 2014 3:07 pm

I just got back from the range with 3 .243s...All 3 shot 100 yard groups.

From the Tikka T3LH with a 1:10, I printed a group of 0.06" with Winchester Ballistic Silvertips, 95 grains. (Not my Rifle, and not a typo)

From the Wnchester 670A with a 1:12, I printed a group of 0.11" with Hornady Superformance 95 grain SSTs. Same rifle printed a 0.48" group with Winchester 100 grain slugs, a 0.55" group with 105 grain Hornady Match and 0.28" with 65 grain Hornady VMax.

From the Rem 700 with the 1:9 twist, the Hornady Superformance 95 grain SSTs printed 0.37", the 105 Hornady match was 0.31" and the 65 grain Hornady VMax was 0.71".

That is 3 rifles with different loads and twists and all were sub-MOA. The Superformance was a factory load, the rest were handloads. Yes, I was on today and the range conditions were perfect. I also shot a 5 round 100 yard group with my 22AR that was 0.52". And yes, I got to make new entries in my log book for all time best groups. Just wish there was a High Power match today. :)
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