I guess it probably depends on how far back a person is going to start counting, but I'm going to guess that in the last 100-120 years, or so, the top 5 list of total big game numbers killed would look something like this:

1. 30/06 SPR
2. 30-30 WCF
3. 308 Win
4. 270 Win
5. 7mm Rem Mag / 300 Win Mag (about tied... slight edge to the 7-Mag)

The 45-70 would certainly be listed if we go way back to the early days with buffalo kills and all, but I think that is a bit nonsensical for this discussion.

Someone mentioned that people these days seem to hate the 7mm Remington Mag. I don't find that true at all and know many very seasoned outdoorsmen who use the 7-Mag. More so than any other magnum cartridge (300 Win Mag comes a very close second). I mean, come on, the 7mm Mag has basically the power level of an '06 loaded warm, with a tiny bit more range / better BC bullets.... what's not to like about that? I find that only here on the Campfire does the 7 get trashed. I'm not sure why.

P.S. I don't own one... but I would.