question about twist rate for 270WSM

bigamehunter93 · December 22, 2013, 11:24 PM

I have a savage model 12 chambered in 270wsm with what I have measured out to be a 1:12 twist barrel. I am wanting to increase my bullet weight from 130gr to 140 or 150 for mule deer and elk. My question is: Is a 1:12 twist to slow to stabilize a 140 or 150 gr. bullet? am I stuck with the 130's?

reynolds357 · December 23, 2013, 11:43 AM

I am not doubting your measuring abilities, but I would re-measure just to be sure. I am not aware of Savage making the .270 WSM in anything other than 1 in 10".

JD0x0 · December 23, 2013, 01:42 PM

I agree, try measuring again. The most common twist for .277 cal is 1:10. And for good reason. It can stabilize almost every weight bullet until you get into the real heavy VLD profile bullets. A 1:10 will stabilize a 180 grain PP flatbase, semi-spitzer in .277 but not a 175 grain VLD. Bullet length is more important than weight. But heavier bullets do tend to be longer.
I doubt your rifle is 1:12 because, apparently 1:11 is the minimum needed to stabilize 130 grain boat tails in .270 Winchester. I seriously doubt the velocity increase from the WSM would allow you to use a 1:12 with the same bullets, but I could be wrong. But that would probably mean, at milder loads, the bullets wont stabilize because they aren't being pushed fast enough.
My guess is your rifle is a 1:10 twist and even the longest 150 grain bullets should stabilize fine.

I mean, if you think about it, what would a manufacture's reasoning behind putting a 1:12 twist in a .270 WSM barrel? It would sort of ruin the point of the cartridge. .270 win will push 130's to 3200fps already. More than enough for game, and flat shooting trajectory. The WSM is supposed to be the 'big brother' of the .270 win and capable of hunting large game at long(ish) ranges. This usually requires heavy bullets with relatively high BC's and sectional density. A 1:12 twist would completely ruin the rifle's ability to shoot the appropriate ammo, and you'd essentially have a severely overpowered deer/varmint gun that will do nothing over a .243 or .270 win, except more meat destruction.

December 22, 2013, 11:24 PM	#1
bigamehunter93 Member Join Date: March 27, 2010 Posts: 55	question about twist rate for 270WSM I have a savage model 12 chambered in 270wsm with what I have measured out to be a 1:12 twist barrel. I am wanting to increase my bullet weight from 130gr to 140 or 150 for mule deer and elk. My question is: Is a 1:12 twist to slow to stabilize a 140 or 150 gr. bullet? am I stuck with the 130's? __________________ " It's easier close the distance by pulling the trigger than by walking 800 yards up the mountain, that is, if your gun will let you."

December 23, 2013, 01:42 PM	#3
JD0x0 Senior Member Join Date: January 30, 2013 Posts: 1,037	I agree, try measuring again. The most common twist for .277 cal is 1:10. And for good reason. It can stabilize almost every weight bullet until you get into the real heavy VLD profile bullets. A 1:10 will stabilize a 180 grain PP flatbase, semi-spitzer in .277 but not a 175 grain VLD. Bullet length is more important than weight. But heavier bullets do tend to be longer. I doubt your rifle is 1:12 because, apparently 1:11 is the minimum needed to stabilize 130 grain boat tails in .270 Winchester. I seriously doubt the velocity increase from the WSM would allow you to use a 1:12 with the same bullets, but I could be wrong. But that would probably mean, at milder loads, the bullets wont stabilize because they aren't being pushed fast enough. My guess is your rifle is a 1:10 twist and even the longest 150 grain bullets should stabilize fine. I mean, if you think about it, what would a manufacture's reasoning behind putting a 1:12 twist in a .270 WSM barrel? It would sort of ruin the point of the cartridge. .270 win will push 130's to 3200fps already. More than enough for game, and flat shooting trajectory. The WSM is supposed to be the 'big brother' of the .270 win and capable of hunting large game at long(ish) ranges. This usually requires heavy bullets with relatively high BC's and sectional density. A 1:12 twist would completely ruin the rifle's ability to shoot the appropriate ammo, and you'd essentially have a severely overpowered deer/varmint gun that will do nothing over a .243 or .270 win, except more meat destruction. Last edited by JD0x0; December 23, 2013 at 01:49 PM.

December 23, 2013, 11:43 AM	#2
reynolds357 Senior Member Join Date: December 10, 2012 Posts: 6,165	I am not doubting your measuring abilities, but I would re-measure just to be sure. I am not aware of Savage making the .270 WSM in anything other than 1 in 10".