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Old March 17, 2009, 09:00 AM   #1
tpcollins
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Bullet weight limit for .243 1-10" twist?

I stumbled across an article awhile back and can't relocate it now. I thought I read that for a .243 1-10" twist, 100 grain bullets would not stabilize well and one should stay with 90 grains or lower.

Am I correct in this understanding and if so, is there a low grain limit for this twist? Thanks.
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Old March 17, 2009, 10:22 AM   #2
FrankenMauser
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My .243 has a 1 in 10" rate of twist.

100 grain bullets (especially the longer designs) do not stabilize well. Some bullets will key-hole at 50 yards. The bullets that fly straight give me the meat-axe effect. -They immediately de-stabilize when striking a target, and tumble like crazy.

On the low end, I can't shoot much of anything under 65 grains.
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Old March 17, 2009, 02:58 PM   #3
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Barrel maker Lilja says the 10" twist is ideal for 90 & 100 grain bullets in 0.243, while Shilen says 10" twist can be used for bullets up to 120 gr. and VLD under 100 gr.

I have a custom 6mmRem with 10" twist. I can shoot accurately with 55 grain thru 105 grain.
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Old March 19, 2009, 03:08 PM   #4
James R. Burke
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Just got the wife a Ruger No 1 .243 that has a 1"to 9". She got her first two deer with it using 100grain Nosler partitions. They shoot under 1" five shot groups at 100 yard. I have not tryed to many differnt loads thru it yet. I have tryed the Nosler 55 grain, and that will shoot under 1" five shot groups at 100 yards. I know this is probably not much help to you, but just a limited amount of info I have on it. Keep it safe, and have fun!
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Old March 19, 2009, 04:29 PM   #5
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The thing about twist rate is: its not so much weight as length. A BT bullet is longer than a FB bullet of equal or greater weight. The BT may weigh less but it needs a faster twist to stabilize due to its longer length. Velocity plays a big part also. Determining twist rate is a science unto itself.

A 243 with the standard 1-10 twist bullet will stabilize "Most" 243/6mm bullets on the market from 75-115grs. The 243 beat the heck out of the 244 for just this reason back when cars had fins. Winchester rifled their guns to stabilize a heavier/Longer bullet than Remington(243 WIN= 1-10" where the 244 REM was a 1-12") Even though the 244/6mm Remington has more Ballistic potential than the 243 the fact that the Winchester could shoot Heavier/longer bullets made it the choice for a Varmint/Deer rifle over the more Varmint oriented 244 Rem. Remington corrected themselves and renamed the 244 to 6mm Remington and changed the twist rate to 1-9". Now very few people shoot the 6mm Remington(the damage was done), a very good cartridge and the 243 is the "Standard" Varmint/Deer gun. The other reason is the action length. The 243, based on the 308 is a true short action where the 6mm Rem, based on the 7x57mm Mauser is kind of an "In between" size like the 257 Robts.

Remington got them back though when they came out with the 22-250 and winchester brought out the 225. Try finding a 225 Winchester.

I hope this helped some and I will say that me personally, I like the 6mm Rem.
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Old March 19, 2009, 07:21 PM   #6
tom234
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Calibers And Twists
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Old October 10, 2017, 09:50 AM   #7
the blur
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Great information to bring back to life.

I'm shooting a Browning BAR 1 - 10. and looking for the heaviest load possible... to get out 300 yards.
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Old October 10, 2017, 12:00 PM   #8
Marco Califo
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Search on stability calculator, or bullet length, or all those words. I have a link on my computer, but not on my phone.
The calculator works. It gives you a value, IIRC 1.4 as a target. I used the longest and heaviest bullet I could stabilize. It calculated right at the threshold, and shoots very well out to 700 yards (max at mu range).
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Old October 10, 2017, 12:06 PM   #9
T. O'Heir
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OP is 8 years old. Mind you, a .243 shouldn't have a 1 in 10 twist, but it doesn't matter much anyway.
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Old October 10, 2017, 12:34 PM   #10
the blur
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Doesn't matter how old the OP is. Still good & valid information. Browning produces their rifles with 1-10. Which kills deer pretty good.

Now I plan to use my BAR at longer distances. So I need a heavier bullet.. and need to know how heavy I can go with a 1-10 twist.
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Old October 10, 2017, 01:07 PM   #11
ShootistPRS
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If you want heavy bullets with your twist stay with flat based bullets that are cup and core design. If you switch to copper bullets they are longer for the same weight and you will find your heavy bullets tumbling.
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Old October 10, 2017, 10:05 PM   #12
Marco Califo
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For OP

1:10" is a good twist rate for most rifles. As noted below, championships have been won with 243 using faster twists and even heavier bullets.

The answer to your question is best answered with Stability Calculator. Follow this link, http://jbmballistics.com/ballistics/.../lengths.shtml
note your bullet length, then click on the calculators in the upper left corner. Then select Stability at the bottom.

"Stability
The Miller stability value. It should be between 1.3 and 2.0 to ensure stability (the military uses 1.5)." I read somewhere else that 1.4 was good (stable) Higher is more stable

The Sierra 100.0 grn SBT (a hunting bullet) gave these Marginal results at 2800 fps:
Cal¡ber:
Bullet Length:
Munie Velocity:
Temperature:
Stability:
Stability
Input Data
0.243 in Bullet Weight:
1.078 in Plastic Tip Length:
2800.0 ft/s Barrel Twist:
59.0 °F Pressure:
Output Data
100.0 gr
0.000 in
10.0 in
29.92 in Hg
Stability: 1.346 Marginal

While the same weight but slightly slower flat base give Excellent results:
Stability
Input Data
Caliber: 0.243 in Bullet Weight: 100.0 gr
Bullet Length: 1.041 in Plastic Tip Length: 0.000 in
Muzzle Velocity: 2600.0 ttls Barrel Twist: 10.0 in
Temperature: 59.0 °F Pressure: 29.92 in Hg
Output Data
Stability: 1.469 Excellent

My recommendation is that you try the Sierra #1540 100 gr flat base and see how they work in your rifle. I think they will be stable and shoot well (not spray all over or keyhole).

OHeir wrote:
Quote:
Mind you, a .243 shouldn't have a 1 in 10 twist
This statement is untrue, as well as not supported ANY facts.
I also have no idea what he means. Does he opine that 1:10" is too slow? Or too fast? 1:10" is fairly midstream as rifle twists go. You need faster twists with longer and heavier bullets. 1:12 would be typical for Varmint rifles with light bullets.
Sierra used a 1:9.125" twist barrel for their load data, while recommending 1:8 or 1:7" twist for Sierra 107 grain HPBT MatchKing. Savage and Remington sell rifles with 1:9.125" twist. http://www.accurateshooter.com/cartridge-guides/243win/
"In 1993, G. David Tubb used the 243 to win both the Highpower Championships at Camp Perry, Ohio, and the National Silhouette Championships (both heavy and hunting rifle), at Raton, New Mexico. The Sierra 107 grain HPBT MatchKing that David used in these matches requires a fast-twist barrel to properly stabilize. We recommend this bullet be used in a 1x7” or 1x8” twist for optimum results."
Howa's 243 has a 1:10 twist.
http://www.howarifles.eu/resources/HOWA.pdf
It is impossible to determine where OHeir gets his mis-information, or why, since he makes statements of opinions, as if they were facts, with ZERO factual support. And very often, as here, they are useless, un-supported, potentially misleading, and obviously wrong.
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Last edited by Marco Califo; October 10, 2017 at 10:14 PM. Reason: Add recommendation
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Old October 11, 2017, 12:52 AM   #13
FrankenMauser
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Quote:
Doesn't matter how old the OP is. Still good & valid information. Browning produces their rifles with 1-10. Which kills deer pretty good.

Now I plan to use my BAR at longer distances. So I need a heavier bullet.. and need to know how heavy I can go with a 1-10 twist.
Good? ... maybe.
Valid? ... debatable.

We've had a lot of discussions about .243 bullet weights and twist rates since 2009 -- many of them with much better information that this one had in 2009.
And, there are a lot more (and different) bullets on the market now, than there were 8 years ago.


...Not to mention that tpcollins has moved on; and that none of the other original posters, other than myself, has visited the forum in the last six months (at least one of them hasn't logged in since 4+ years ago).
It's an old thread that deserved the death that it got. Let it go.
If you want to discuss .243 Win twist rates, start a new thread.
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