In truth many cape buff have been shot dead with a 338 WM w\250 gr - 270 gr loads (yes the 338 WM has been used on buff in Africa), can’t say the same for a 300 WM using any load. If raw numbers mean anything, the 338 WM is a closer comparison in performance to a 375 H&H when used on very large game. That’s not to say the 300 WM isn’t potent and a great performer. Again higher impact velocity w/ lighter weight bullet doesn’t necessarily translate into deeper penetration. More moderate velocity with heavy projectiles usually translates into maximizing both penetration and expansion. There’s a time and a place for using either. Depending on what you hunt, you’ll probably get more NA field use from a 300 WM by far.