In response to the original poster . . . I have to say, his comments about the .17 HMR have merit. Expensive as heck . . . if I wanted a very small varmint cartridge with less bark than a .223, I'd get a .22 Hornet. Today's .17 HMR reminds me of yesterday's 5mm Remington Magnum rimfire with a better press package. (And now we have TWO .17 rimfires that aren't interchangeable!)
.30 Carbine . . . not much use for one. Maybe war stories I heard from veterans with 1st hand experience about this cartridges inability to
reliably down an enemy soldier have colored my opinion.
.204 Ruger . . . this oddball proprietary cartridge is an answer in search of a problem. (I'd also add Ruger's .480 in here, too.)
7.62x39 . . . here, we start to part ways. This is good, cheap plinking ammo, considerably more potent than .30 carbine, and is cheap to shoot in extremely reliable AK-pattern rifles and extremely cheap SKSs. Mild recoil, adequate for deer . . . and did I mention it was cheap to shoot? Sometimes,
price is, in itself, an endearing quality.
And bad mouthing "all MAG cartridges" including the .375 H&H . . .
I've found - first hand - that the .375 is darned near ideal for large game, including lion, hippo, a couple of Cape buffalo, etc. Badmouthing the .375 is borderline heresy!
Personally, though, I'd add the new "short magnum" cartridges to the list. Despite what the writers in the gun rags insist, I've never found saving 1/2" of length in the action to be significant, or even noticeable. So cartridges like the .300 WSM and it's NON-interchangeable twin from Remington just hold no interest from me. Nor do the spinoff cartridges. Maybe the short & stubby case will have some attraction for hardcore benchrest shooters, but not me.
Still puzzled at the .450 Marlin and .45 GAP. Oddballs both.
Likewise the super-duper .300's like the .300/.378 Weatherby. I'm no acolyte of Jeff Cooper, but I think he has it right when he says that if the .30/06 isn't enough, you need more bullet, not more velocity.