He’s referring to a little thing called sectional density. The conclusion you have drawn is gravely in error.
Wab, I am sorry but you and thriller are wrong about that. I assume that you are saying that large diameter bullets have poorer penetration on cape buffalo. Am I right?
SD theory is very misleading regarding terminal ballistics. That is a proven fact. The SD theory is proven to be generally outdated. ( please just research recent tests and discoveries on the subject.)
I hunt cape buffalo with a 50-110 , 410 grain flat nose bullet CEB, ay 1,920 fps MV. and .577 NE, 700 grain Peregrine Bushmaster bullet at 1,850 fps MV, and the penetration is excellent, usually the bullet makes it through the ribs on the far side.
One of the best places to get up to speed on the topic, other than actually hunting a lot of cape buffalo with different cartridges, is to read B&M rifles and cartridges. ( There are other excellent sources as well.)
B&M did extensive, focused R&D for nearly a decade on Africa and Australia buffalo and in their wet medium lab in the USA, when they developed what came to be know as the CEB line of dangerous game bullets. The main goal of their work was to maximize straight line penetration while creating a wide, permanent wound channel with big bore bullets. ( Their innovative Safari Raptor bullet work a bit differently than conventional bulltes. That's another story.)
The fruits of their labor is a huge gift to all us hunters if we want to have it. Some of the old theories and beliefs about hunting bullets terminal performance, have just not stood up under modern research.
Honestly, I don't emphasize this to belittle you or discredit you, or anybody. I have been preaching about bullet terminal performance because I am just a bullet nut.
I have been hunting large game animals since 1958 an in the last decade I have become very curious about the current developments in hunting bullets design especially for cape buffalo I love to talk about it and to pass on what I happen learned.
I can't take any credit for any of this. It all just intrigued me. I am the curious type and really got into studying everything that I could find on it.
I started out with Swift A-Frame bullets in my .375 HH for Africa hunting, then I stumbled across NorthFork SS expanding bullets before John sold the company to the good folks in Sweden. Next I gave CEB bullets a test drive on cape buffalo and I was hooked on high quality bullet and became an avid student of bullet terminal performance.
I know that, in my enthusiasm I come across as a P.I.A. at times. I assure you I mean nothing by it, I just roar over the top when I get talking about hunting bullets.
As I say my curiosity has led me to a good place in selecting hunting bullet for cape buffalo which is all that I hunt now.
Happy hunting to both of you, I wish you both the best, Brian