Barrel twist rate recommendations are for the caliber, not the chambering. So, it would be the for .338 WM or .338 LM. The bullet in question requires 1:8" or faster. Does your .338 WM has the required twist to stabilize the bullet? These bullets are long; do you have OAL for your action to accommodate it? I limit my .338 WM to .225g, Good luck!