ORIGINAL: ths78
I'm gonna go out on a limb here and say that a 243 probably delivers as much energy on target on deer/antelope size game as much more powerful cartridges do, like the 300 win mag. Yes the 300 has a much more power, but once it passes through the deer, it's not of any use any more. This is just a guess though, as I've never read any credible sources that proved this argument.
That said, I do not believe energy means much when it comes to killing power. For example, a 45 LC pistol only has about 300lbs ME but will cleanly kill any deer out to 50 yds with a 300 gr cast bullet. I believe shot placement and wound diameter are most important.
I've never seen a 243 used on deer, but have seen a 257 Roberts, and it is pretty much the same thing. It works just as well as my 7 Mag, 30-06, 308, and 45-70 inside of 200 yds, and better than my 44 Mag and 30-30.
That is truly the worst theoryI have ever heard, look at the ballistics, the .300 Win Mag has a lot more energy, it just depends on what bullet you use, as far as pass throughs go, so, no, the .243 doesn't have anymore contact power then the .300 Win mag, it's impossible. And, energy does mean quite a bit in killing power, bullet diameter doesn't, I used to have the mind set, that the 45-70 was superior to the 416 Rigby, and similar calibers, because it had a larger bullet, that is not true, the 45-70 just cannot match the .416 Rigby, when it comes to power, I'm not gonna argue with you, as it would be a waste of time, if you think those big bullets, with their rainbow trajectory, kill game better, then that is your problem.