The extra speed makes perfect sense with the shape of the bullet.

Too, the larger the diameter of the bullet, the slower they can be going to get a similar result. The .458's or .510's could be moving slower yet and still produce the cavitation necessary to get fluids in motion to create extensive damage beyond the bullet's diameter.

Remember the clean wound around the stopped .450/.400 bullet that went full length of the buff and was found in his neck?

Around the bullet where it was dug out there was literally no damage at all, it has slowed to a stop at that point. Obviously, back a ways in it's path, though, the bullet had done it's job and created all the damage reuqired. When they are moving slowly, solids create very neat wounds. When driven quickly, they can cause cavitation, the better shaped to accentuate this trait, the more cavitation they create.

Even flat nosed bullets create this cavitation, which is why flat nose bullets are preferred for hunting with the old standard handguns & BP or low rifle ctgs. The flat nose creates more damage than a round nose. A cup-nose, as in the Hydro, obviously creates more damage yet.

Due to the non-expansion trait of the bullets, they are relying upon the shape and speed of penetration to create the cavitation. A bullet that slows quickly, will reduce the total damage. Since speed during penetration is required, heavy game requiring deeper penetration actually requires a longer hydro. What I'm getting at, is that on deer, a 235gr. .375 Hydro might be best, kill the fastest,due to producing the greater cavitation in that animal however on a buffalo reuiring greater penetration, a 270gr. or 300 would be preferred due to the greater sectional density. It all comes to balance - use what's appropriate.

Obviously, the 225 gr. is a good .358" Sambar bullet. A 200gr. driven at 3,000fps initial velocity might be better yet, on those animals. It would certainly create a "cavity".