My .270 AI has a 30" Lilja 1:8" 3G #6 contour.
I shot 140s with my .270 AI with 1:8" without any problems. I primarily shoot the 175 Matrix VLDs.Thanks for all the good replies.
I checked out Berger's Twist Rate Calculator and looks like anywhere from a 8:1 to 10:1 would work for a 140gr to 150gr bullet. But when I go to the 170gr VLD it looks like I want a 8.5:1 minimum. Do the barrel guys even make a 8.5:1 or are you limited to 8:1 or 9:1?
If I went with a 8:1 over the 9:1 what would I be giving up with the 140s and 150s? Anything? Or in other words, why would I not want to go with a 8:1 since it'll also handle the 170s?
No reason not too....im building a .270 sherman max and using a 1:8 tw...but i plan on using 170 bergers and a heavy type hammer/cutting edge bullet. I also live in louisiana with low altitude, high humidity and cold mornings that could destabilize the bullet if i dont esp with copper solids. I found a .270 8tw here for sale otherwise i would have got an 1:7.5 tw if i would have ordered a barrel.
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
Twist Calculator
The Barrel Outlet's Barrel Twist Calculator Calculator is a tool for determining the Gyroscopic Stability (GS) of your bullet and is based on the Don Miller twist rule. (Learn More). This calculator is used to find the optimal twist rate for your bullet. This is a general information...thebarreloutlet.com