11 twist 7mm barrel

C

CWPINST

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I have been told (by Shilen) that a 140gr. Ballistic Tip is about the longest bullet that an 11 twist 7mm barrel will stabilize. Can you go safely higher, such as a 150gr. Ballistic Tip? I measured a 140gr. Ballistic Tip to be 1.260 in. and a 150gr. to be 1.300. Caliber will be 7mm-08.

Thanks
 
I have a 1:11 twist Shilen barrel on my 7-08AI. I've shot a few different makes of 140gr bullets up to 3075fps with H414. Accuracy isn't as good as it is with IMR4350 or IMR4831 at 2950-3000fps, but they don't keyhole. I haven't tried anything longer than 140gr Ballistic Tips. A slightly longer bullet might stabilize if you have enough velocity behind it, so it might depend on what you're shooting. I built mine with the 11 twist barrel because I planned on keeping by bullet weight to 140gr or less. I always figured that I would just grab my 300WinMag if 140gr from my 7-08AI wasn't enough gun.
Sam
 
the standard, shoot anything twist for 7mm is 1:9". I have a 280 AI with a 10" twist that shoots 140 gr and 150 gr bullets very well. I have a 9" twist 280 AI that shoots 140 gr and 160 gr bullets even better. If I thought that I might want to shoot heavier bullets, I would just get the 9" twist and not worry about it. The Remington 7mm-08 barrels are a 9.25" twist and generally shoot the lighter bullets just fine. I think a good quality barrel shooting well made bullets in a hunting caliber is going to be tough to see any difference with a faster than optimum twist rate. You may not get quite as much velocity with a faster twist, but thats why Remington came up with the 280 and Ackley fireformed his cases in an improved chamber.
 
CWPINST said:
I have been told (by Shilen) that a 140gr. Ballistic Tip is about the longest bullet that an 11 twist 7mm barrel will stabilize.
Click to expand...

I've owned two of the barrels you mention and they shot the 150 SGK's very good but, they were very soft. In February, I orderd another 7mm Barrel, it was a 9 twist Krieger. I think anything other than a 9 twist 7mm barrel would limit you to the lighter bullets, 120/140/150 class. I've shot the 120 BT's from a 9.25 twist Remington barrel with good results to 420 yards, a little light for deer though IMHO. For everyday hunting with a 7/08 the 11 twist and 140/150's would fill up the truck, I just prefer a faster twist so a heavier bullet could be employed.
 
I don't plan on shooting anything heavier than a 150gr, In fact, 140 is about as light as I plan on going. I went to one website and filled in the info. on the 140 NBT @1.260 with the 11 twist. The stability factor came out to be only 1.18. This particular site was in Canada and didn't ask if it was a boattail bullet or FB. It just asked for the length, caliber, velocity and twist, so I don't know how accurate the results are.
 
Length is what matters, not bullet weight. The very long 150gr may not stabilize, whereas the shorter ones may, like a cup and core flat base (not the solid copper types).
Sam
 
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