Originally Posted by 150pilot
I was going to get Barnes 130 TTSX's but the Barnes site warns that it won't stabilize with that twist. My understanding is I need a bullet that isn't going to be too long for it's weight and that Barnes TTSX 110's should be fine. I may go that route, but I would have preferred something just a bit heavier.
Barnes' comments are wrong as most other manufactureres' sites on twist rate for bullets. It stems from decades ago data when folks chambered their existing barrels for a larger case and got decent results...as they tested them. Note the .30-03 cartridges 220-gr. bullet did great with a 1:10 twist. When it was replaced with the .30-06 and 150 grain bullets, they didn't shoot as accurate as 172-gr. heavy machine gun bullets which benefited from that faster twist.
Bullets need to spin at some small band of rpm's to stabilize at the velicities we shoot them at. The .270 Win. was first chambered with a 1:10 twist and that's perfect for 150 to 160 grain bullets in it.....at the muzzle velicities that case shoots 'em out at. A larger case producing higher muzzle velocities can use a slower twist. If that wasn't true, then folks shooting 155 grain 30 caliber bullets from rifles at 3000+ fps getting 1/2 MOA accuracy at 1000 would have never happened. And the 7.62 NATO round would not have been spec'd with a 1:12 twist for 147-gr. bullets leaving slower than the 150-gr. ones form 30 caliber Garnands' .30-06 1:10 twist barrels.
Shoot those medium and heavy weight bullets out of your .270 Wby.'s 1:12 twist barrel. It's great for that case size and velocity it produces. A 1:13 twist may even be better. Spinning bullets too fast tyically makes 'em shoot less accurate. Bullets with too much slight imbalance spun too fast make's 'em jump sideways a bit too far from centrifugal forces when the leave the barrel.