Read Gregor Woods' book about African rifles and you will get similar opinions. I have noticed this to be especially true with muzzleloaders which don't generate a lot of muzzle energy because of low velocities. In spite of that, I've taken a lot of big game with 400 grain muzzleloader projectiles traveling at 1350 FPS and witnessed outstanding trauma effects. On an Indian River Buffalo hunt a 600-grain muzzleloader slug over 120 grains of powder exhibited better penetration and bullet performance than a .470 using solids at the same range. While I don't know if this is a practical or consistent observation, it was certainly impressive at that time.