I'm sorry but I have to look beyond the dead critter. If that is the only criteria for determining what works, then chunks of rebar out of a fabricated muzzleloader and .22's are sufficient for elephant. After 30yrs of doing it and studying it, I know too much about the sport to even consider a 200gr 10mm on Cape buffalo to be anything but the irresponsible stunt that it is.
There's nothing magic about the 10mm. All the same rules apply. There's no secret recipe that's going to make it as effective as a .475 or .500Linebaugh. There's a dozen of us descending upon Texas in a little over a week to hunt bovines ranging from 1000lb watusi to 2000lb water buffalo and there won't be a single 10mm in the crowd. There will be a selection of heavily loaded revolvers in .41Mag, .44Mag, .45Colt, .454Casull, .475Linebaugh, .500JRH, etc., and there is a mighty good reason for that. Even the .500's don't seem like enough gun when the action starts. You can't take too much gun but you can sure as hell take too little.
I also would never hunt something like Cape buffalo with a weapon that couldn't possibly stop a charge. There are some great ~.400" cartridges for Cape buffalo but they're about three inches long and launch 400gr at a time.
All that said, the next time I setup to do penetration testing in SIMTEST, I'm going to test several heavy 10mm loads to see where they stand.