I'm thinking of loading some 200-220gr. and wonder if 1in 11" twist will stabilize them at around 2500fps. Thanks, James
Best twist rate for heavy 30.06
- Thread starter Jacks Grampa
- Start date
Liven The Dream
Gold $$ Contributor
Old Standard 1-10 !
eleven would probably work but the only reason I can think of for buying an eleven over a ten would be that it is way cheaper! WH
The bullet form factor is relevant. A 220 Hybrid Target requires more twist than a 220 round nose. Regardless, as noted above, 10" twist will do almost anything you want in .30-'06.
Thanks all. I'm looking at a 700CDL that is 1-10.
Ned Ludd
Silver $$ Contributor
James - if you have the intended bullets in hand or know their OALs, you can plug the numbers in here and see what different twist rates will buy you in terms of stability in various conditions:
bergerbullets.com
I would suggest a minimum gyroscopic stability coefficient (Sg) of maybe 1.3, although somewhere in the 1.4-1.5 range would be better. These numbers aren't written in stone, meaning the bullet won't suddenly fall out of the sky at an Sg slightly under 1.3, nor will they spin apart at an Sg of slightly greater than 1.5. However, you really don't want to go below about 1.1 or so, because bullet stability will become a major issue. The key is to match the barrel twist rate of the barrel with the bullet at its expected velocity so as to obtain the full intrinsic BC; i.e. "performance" of the bullet. According to Bryan Litz, this occurs at Sg values of 1.5 or greater. Nonetheless, I've shot a lot of bullets at Sg values in the upper 1.3s to low 1.4s and they worked just fine, even though I probably wasn't getting the full BC of the bullet.
FWIW - I've run Berger's 200.20X bullet out of an 03' Springfield with a 24" 10-twist barrel at around 2500-2550 fps and it shot very well. I've shot the same bullet out of an F-TR rifle with a 30" 11-twist barrel at approximately 2650 fps, and it also shot very well. However, the difference in twist rates between the two barrels was compensated to some extent by the extra 100 fps velocity obtained with the longer 30" 11-twist barrel. At 2500-2550 fps, an 11-twist barrel may be a bit slow for the 200.20X bullet, generating Sg values of less than 1.3 in cooler temps and/or at low elevation. The lengths of the actual 200-220 gr bullets you intend to use will affect the outputs, so having those values will be helpful for using the Twist Rate Calculator.
I'd go with a 1:10 twist as others have also suggested, but if all you have is an 11-twist barrel, you could still try it and see whether it was fully stabilizing the bullets. If you observe slightly oval or oblong holes in the target, the twist rate is insufficient. In that event, something in the 185 gr range would probably be a better way to go.
Twist Rate Stability Calculator
Our newly updated Twist Rate Stability Calculator not only tells you what your SG is, but it also lets you know if you are reaching your optimized BC.
bergerbullets.com
I would suggest a minimum gyroscopic stability coefficient (Sg) of maybe 1.3, although somewhere in the 1.4-1.5 range would be better. These numbers aren't written in stone, meaning the bullet won't suddenly fall out of the sky at an Sg slightly under 1.3, nor will they spin apart at an Sg of slightly greater than 1.5. However, you really don't want to go below about 1.1 or so, because bullet stability will become a major issue. The key is to match the barrel twist rate of the barrel with the bullet at its expected velocity so as to obtain the full intrinsic BC; i.e. "performance" of the bullet. According to Bryan Litz, this occurs at Sg values of 1.5 or greater. Nonetheless, I've shot a lot of bullets at Sg values in the upper 1.3s to low 1.4s and they worked just fine, even though I probably wasn't getting the full BC of the bullet.
FWIW - I've run Berger's 200.20X bullet out of an 03' Springfield with a 24" 10-twist barrel at around 2500-2550 fps and it shot very well. I've shot the same bullet out of an F-TR rifle with a 30" 11-twist barrel at approximately 2650 fps, and it also shot very well. However, the difference in twist rates between the two barrels was compensated to some extent by the extra 100 fps velocity obtained with the longer 30" 11-twist barrel. At 2500-2550 fps, an 11-twist barrel may be a bit slow for the 200.20X bullet, generating Sg values of less than 1.3 in cooler temps and/or at low elevation. The lengths of the actual 200-220 gr bullets you intend to use will affect the outputs, so having those values will be helpful for using the Twist Rate Calculator.
I'd go with a 1:10 twist as others have also suggested, but if all you have is an 11-twist barrel, you could still try it and see whether it was fully stabilizing the bullets. If you observe slightly oval or oblong holes in the target, the twist rate is insufficient. In that event, something in the 185 gr range would probably be a better way to go.
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My last two 308 Win were 9 and 8 twist... 9 twist recommended on the box for 200 gr SMK ...8 twist recommended on the box for 230 gr SMK. The 9 twist is a 22" hunting rifle runs the 200 SMK .715 BC at 2740 fps, and shoots them well. The 8 twist is a long action 30" 308 shoots 200 SMK at 2856 fps 225gr ELDM 2675 fps & 230 Atip at 2630 fps...
Check Hornady site for comparison of BC and twist rate...affirmed by their radar...a big difference. I've been running "faster" twist for several years...300 PRC is 8 twist standard from the factory..."fast" is the 3 twist in the 8.6 Blackout, and that presents some problems with lead bullets...still testing ... but weather isn't cooperating.
Check Hornady site for comparison of BC and twist rate...affirmed by their radar...a big difference. I've been running "faster" twist for several years...300 PRC is 8 twist standard from the factory..."fast" is the 3 twist in the 8.6 Blackout, and that presents some problems with lead bullets...still testing ... but weather isn't cooperating.
Kurz
Silver $$ Contributor
Seemingly the 1:10" twist rate has been a standard for factory barrels nearly forever. Here is a small list of models and twist rates:
30-06 - 1 in 10"...Browning BLR 81, BAR Mark II, A-Bolt II; Colt, FN; High Standard; J.C. Higgins 50, 51, 51-L; H&R 300; Mannlicher-Schoenauer; Marlin; Interarms Musketeer; Rem 721, 760, 740, 742, 725, 700, 40-XB, 7400, 7600; Savage 110, 114, 116 (present); Sako; Schultz & Larsen; Stevens 110; Win 70, 670, 770; Weatherby Vanguard, Mark V; Ruger #1, 77: Wichita; Mossberg; Magnum Research Mountain Eagle; T/C Rifle30-06 - 1 in 12"...HVA; Rem 700V (old);Browning 78, Colt/Sauer
I have shot both the 1:12" and the 1:10" with the older HVA curtailing some bullet designs although it's not a target rifle by any means, it is strictly a hunter. As pointed out above, the longer solids and some of the Match/Target bullets might require a slightly faster 1:10 twist.
I have depended on the Nosler 200 gr. Partition in one of the hunting rifles which satisfies everything I require when carry the .30-06 for elk hunting. This is with the 100V powder yielding about 2600 fps. If you need more energy and velocity switch to Re-16/17 for 100 fps gain.
30-06 - 1 in 10"...Browning BLR 81, BAR Mark II, A-Bolt II; Colt, FN; High Standard; J.C. Higgins 50, 51, 51-L; H&R 300; Mannlicher-Schoenauer; Marlin; Interarms Musketeer; Rem 721, 760, 740, 742, 725, 700, 40-XB, 7400, 7600; Savage 110, 114, 116 (present); Sako; Schultz & Larsen; Stevens 110; Win 70, 670, 770; Weatherby Vanguard, Mark V; Ruger #1, 77: Wichita; Mossberg; Magnum Research Mountain Eagle; T/C Rifle30-06 - 1 in 12"...HVA; Rem 700V (old);Browning 78, Colt/Sauer
I have shot both the 1:12" and the 1:10" with the older HVA curtailing some bullet designs although it's not a target rifle by any means, it is strictly a hunter. As pointed out above, the longer solids and some of the Match/Target bullets might require a slightly faster 1:10 twist.
I have depended on the Nosler 200 gr. Partition in one of the hunting rifles which satisfies everything I require when carry the .30-06 for elk hunting. This is with the 100V powder yielding about 2600 fps. If you need more energy and velocity switch to Re-16/17 for 100 fps gain.
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