The 7mm Remington Magnum is, IMHO, tied with the '06 for the best all-around cartridge for the average North American hunter. Although I'm a big fan of the medium bores for larger game species, the 7 Mag performs very well and with much less recoil (30-06 levels--I can't tell the difference in the real world).
I've taken, and seen taken, many elk and other large game with the 7 Mag and both 160 gr and 175 gr bullets of various brands. Although I favor the 160'ish boat-tails for an all-around loading, the 175 gr Nosler Partition is pure poison on big bull elk, moose and bear.
In regards to the effective range of the 7mm Remington Magnum, I think it boils down to the individual shooter more than anything. The 7 Mag with a 160 gr boat-tail has the trajectory and energy numbers to easily dispatch an elk at over 400 yards (if the shooter does his/her part). The furthest shot I've personally taken on a bull with the 7 Mag was 420 yards (with the 175 gr load). The bullet broke the far shoulder when exiting and the bull took two or three stuttering steps and piled up.
It's a great, easy-to-shoot cartridge and any of the good 160s to 175s will do a number on elk out to about as far as one ought to be shootin'.
