I don't have a micrometer but my .270 Win 165 grain cartridge is very close to 3.375" COAL. It should work with a 3.4" magazine. My magazine is from a Rem 700 long action.
At 900' elevation in 80 degree temps, I get .310 BC at 2840 fps with the 24" 1:10 twist. My stability should degrade in lower elevation and/or colder temps. Stability should improve in higher elevation and/or warmer temps.
The faster the velocity, the less twist you need; that is why I am sending the bullet at max velocity. I'd much rather have a 1:9 twist but accuracy and BC are very good, especially when hunting in high elevation. I will change to 1:9 when I need a new barrel.
The Elk attached dropped immediately. I am absolutely comfortable with any reasonable shot through the shoulder or vitals with the Matrix 165. The fragmenting load also has a better chance of clipping an artery or the spine in the unfortunate event of a poor shot.
Great looking bull. Looks like H 1000 will be a top choice too for the heavyweights along with RL 26 and IMR 7977. Those 165 gr Matrix sound good.......