I pumped a lot of them into a cape buffalo and then woodleigh hydros. The beast took probably 7 rounds total. Three reasons that could reasonably be the cause:
1.) I strongly suspect my two cases of federal ammunition were not loaded to correct velocity. In another example, that lot of ammo didn't pass through a kudu or zebra.
2.) To quote Pandoro et. al. for more than a century of experiences, a 40 cal bullet going 2150fps and weighing at least 400gr is when the magic happens. 375HH is less than that on two of three factors.
3.) One could suggest my shots weren't exceptional.
If I was going to head out buffalo hunting again, I'd have a 404 Jeff or bigger, and I would use A-Frames for the first shot in any regard. Just how I learn my lessons, but a 375HH is a wonderful do-all nonetheless.