Game animals, and even cattle are a poor basis for measuring the terminal performance of a bullet, since the endless variables of body density, shot angle, range, impact velocity, and so on would require the shooting of hundreds if not thousands of animals. The animal's reaction to the shot would which would then be carefully tabulated, the carcass dissected, with measurements and the weight damaged tissue determined and recorded. This would have to be done in each and every case. The only time anything like this has occurred in North America, to the best of my knowledge is during the Thompson-LaGarde Studies in 1904. In South Africa, a couple of bullet manufacturers conduct live animal shooting as part of their terminal performance studies, but they are the exception to the rule. In North America, bullet manufactures use Billy Bob's field experience as proof that their little pieces of metal are better than the other guy's, and are truly worth the $2 a piece you'll have to pay for them.
There is a problem with taking any one hunter's observations as absolute proof of anything. Let's consider Steward Edward White. White was a marvelous game shot, who was claimed to be able to keep his shots within 2" of his intended point of impact, regardless of range, position, or amount of physical exertion. I wish I could do that. In 1911, the .30/06 was still new, he took the second Wundhammer custom Springfield sporter ever built, the first one belonged to President Roosevelt, on an African safari back when African safaris could last 6 months or more. During that safari, he supplied all of the camp meat with that rifle, and gained a reputation as the greatest game shot that ever lived. It was said he could always place his bullet within 2" of his intended point of impact, regardless of position, range, exertion, or shot angle. Bear in mind this was with an aperture rear sight and a post front sight. I wish I could do that . . . with a scoped rifle. Number of animals that were missed - 0. Number of animals that escaped wounded - 0. Number of animals that required more than a single shot - 6 (IIRC). The bullet that White used to such effect, was the only one that the .30/06 was available with at the time, military ball 150 gr FMJ with a muzzle velocity of 2700 fps. According to his carefully recorded observations, this was a dandy game bullet. If anyone spoke today of using military ball ammunition on big game, they'd be tared and feathered, and unkind rumors would be spread concerning their lineage to canines.
So back to the point I was attempting to make, bullet testing has to be done in such a way that all bullets are measured on an even playing field, and from that data suggestions can be made for which bullet is best, or even acceptable for what job. Sometimes the testing comes close to duplicating field results, other times no so much. Prior to my African trip, I tested 3 bullets, thinking I would choose one for the trip. The testing involved lining up a number of 5 gallon pails filled with drill mud, and shooting into them from 20' distance, which I considered my nightmare buffalo scenario, and I would take the bullet that didn't fail. The first two were 270 and 300 gr .375 X bullets, the 270 gr was an XLC. Both bullets had the petals blown off, and both had a remaining frontal diameter only slightly larger than the shank, but the 380 gr Rhino at 2300 fps was a game changer. It expanded to .92", blew apart the first pail so no cavity measurement could be taken, and stopped in the 3rd pail. Overall penetration was 32"! In the end my .375 Ultra stayed home and I used a .500 Nitro double rifle with 580 gr X bullets at 2150 to slay my buffalo. The bullet I recovered from the buffalo expanded to .92" and penetrated 32" on a quartering shoulder shot. Cool. Should that be taken as how every .510 X bullet would always perform on buffalo? I wouldn't say so. Everyone knows you can't get a clean kill with a non-expanding bullets on game, but wait a minute, on the same hunt, with my partner's M-70 .375 H&H, and 300 gr Speer African Solids, I got 2 DRTs, an impala and a warthog. Maybe Stewart Edward White was on to something.