After some more experience I decided that one overnight deer was just one of those things.
It only went about 75 yards, but into really thick stuff, and there wasn't any blood trail. I was hunting with an older guy who didn't have much patience with my claim that the crosshairs were in the right place when the rifle went off. We were hunting in his pickup, and after looking for more than an hour he said he had to get home.
I didn't sleep much that night and insisted we go back the next day--and I found the deer within minutes, thanks to a magpie coming out of the thick stuff. Turned out I hit it perfectly, too, right through the top of the heart. The bullet (a 105-grain Speer Hot-Cor) also appeared to work perfectly, since there was about a 1" hole through the heart.
Since then I've seen a lot of rounds sometimes result in more or less the same thing, including a .300 Winchester Magnum loaded with 200-grain Partitions. As a result of those experiences (and others) I don't believe nearly as much in the difference between most cartridges as many people too--or I used to.
My change of attitude about the 6mm's hasn't been so much the new bullets but seeing a lot more game taken, with a lot of different rounds and bullets.
