Proper twist rate

[Muddly]

My Savage 110 is giving decent accuracy with 95 grain Hornady SST's and I'm trying the 100 grain Sierra Pro Hunters.
On a lark, I used Greenhill's formula and both bullets apparently need a 1-8! I believe my Savage is a 1-9 1/4. I'm getting decent accuracy, 3 rounders at 100 are in the inch range and sometimes smaller. At some point I'm going to need a new barrel. I'm a deer hunter, so the 95 - 100 trainers are where I want to be. So do I go 1-8?
I'm confused...

[MRCHIRO]

My Savage 110 is giving decent accuracy with 95 grain Hornady SST's and I'm trying the 100 grain Sierra Pro Hunters.
On a lark, I used Greenhill's formula and both bullets apparently need a 1-8! I believe my Savage is a 1-9 1/4. I'm getting decent accuracy, 3 rounders at 100 are in the inch range and sometimes smaller. At some point I'm going to need a new barrel. I'm a deer hunter, so the 95 - 100 trainers are where I want to be. So do I go 1-8?
I'm confused...


Well your caliber would be of great assistance to others answering your question bud :)


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[Stumpkiller]

I'm going to guess .243/6mm based on the 95 gr SST & 100 gr Sierra Pro Hunter. (THIS is why I always hated word problems in school).

Winchester uses a 1:10" and does fine with 100 gr bullets. The 6mm Rem came out first in 1:12" and it did not. You should be fine with 1:9.25"

[MRCHIRO]

If 243 your be fine but 10T is normal. Mines 7T for the 115grainers.


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[Evlshnngns]

I have a model 11, it likes the 80 gr silver box Winchester. It will put two in the same hole, wing the next couple out to roughly 3/4. It had similar accuracy to what your saying with the softpoint 100gr Winchester. Some people on here have luck with the old 105 amax if they push it hard enough.

[Muddly]

... My bad. She is a 243 Winchester. In fact, this Savage is the only 243 I've had good results with.
I found another version of Greenhill that has a different stability figure for velocities over 2500 fps. Plugging that figure in, a 10 twist is spot on.
I want to develop some reduced loads, to extend wallet, case and bore life. Curious to see if accuracy holds up if I fling those 100s at 25-2600 fps.

[MRCHIRO]

You’ll be fine. Don’t worry too much and go shoot it:)


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[jim_k]

1:8

[Texas10]

My model 11 in 243 shot the 87 V-Max very well. First two shots at 200 yds would lay next to each other but the third and forth were an inch away. Never tried any of the "long" bullets. As you say, the SG is not so good with the 9.25 twist of the Savage.

But if I were going to change barrels, an 8 twist or even a 7.5 would be great for the heavier bullets, especially at long distances.

http://www.bergerbullets.com/twist-rate-calculator/

[charlie b]

It does depend on a lot of things. Air temp and density will affect the stability if you are 'on the edge'. You can be fine when temps are in the 70's but not so much when they drop to the 30's. And, the longer the range, the more error from marginal stability.





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[jlsbassman]

100 should be fine. My model 11VT runs 105 Amax just fine. I’ve ran it to 1100yds with no issues. Running them around 2980 fps. They shoot great but are getting hard to find.