Ever wonder why the classic Safari cartridges have heavy bullets at or below 2,400 fps? 416 Rigby, which is arguably the "Gold Standard" for a "stopper" has a 400 grain bullet at 2,400 fps, the 375 H&H the "Golden Standard" for medium bores has a 300 grain bullet at 2,400 FPS. Now there are plenty of newer medium and big bore rounds out there, such as the 375 RUM and 458 Lott that have increased velocity over the old standards, but even the "new" wondermagnums are judged against the old standards.Of course, the FBI has standards for penetration tests when shot into ballistic gelatin. There are places to go online to see gel test photos, videos, you name it. It appears to me that all the major calibers, in modern hollowpoint designs penetrate adequately. Whether they behave adequately in a real self defense situation is the subject of endless discussions based on - thankfully! - few real measurements.
AM concludes with this:
To sum it up, no matter what round you are using, heavier bullets are generally the better bet for lethality on large game.Like overweight hippies on PCP.