Twist Rate Overview:

1-13:

Recommended for 150gr loads and for use in extremely cold conditions.

1-15:

Shoots all bullet weights from 95gr to 150gr well, however at extremely cold temperatures of below zero some longer 150gr bullets may become unstable. It is optimal for 95gr-135gr bullets.

Why We Have Two Twist Rates:

When the cartridge was originally developed, we were relying on A1680 powder and couldn't safely reach the velocities we wanted for 150gr bullets. So, we focused on 125gr-130gr load development and the 1-15 twist tested (we tested 1-11.25, 1-12, 1-13, 1-14 and 1-15) out to be the most accurate with these bullet weights. Fast forward to when we discovered CFEBLK. We found that we were no longer limited to 130gr bullets, and that we could actually equal the time proven .30-30 Win velocities with 150gr bullets at safe pressures. At this point we did more testing and found the 1-13 twist to be optimal for 150gr bullets and it eliminated the possibility of a 150gr bullet becoming unstable in extreme cold weather conditions.