Re: 6.5-270 wsm ?
I shoot at 5600 ft elevation + and that lets me stabilize the 165 and 175 in a 1-10 twist, ideally a 1-9 for the 165 would allow you to be stable anywhere.
I'm shooting a 27in barrel chambered with a 270 WSM tight neck and .180 throat, I idle the 165 at 3060fps and the few times I've shot for a 6 shot group at 1000 and 1450 it's been under 1/2 MOA shooting from a bipod. Mostly I cold bore shoot with a follow up round at targets of opportunity. This is a single shot set up with a 3.2 COAL.
A barrel length between 26 and 28 inches is ideal with the WSM.
This last year I've been shooting the 6.5 SS which is a pushed back and blown 6.5 SAUM with a 29 inch barrel, I idle the 140's at 3200 fps and run the 160 Matrix in the 3050-3100 fps range but I have not settle on a spot with them yet, all with proper bullet placement in the neck yet in a short enough package it cycles like butter through a standard short action. I plan on building a 270 version soon so I can use the short action configuration easier and still hunt with the 165 Matrix.
"Pain is weakness leaving your body"