RE: 300 win mag
deer don't go far with a hit from a 7mm. even more, they won't go far if you place your shot perfect. I know many of ppl that hunt deer with a .243 and most hav dropped in their tracks, right where they shot'em. either way, a 300 is a massive cannon gun. and I bet the shells are expensive, I know a box of 7mm are 20+ dollars for just a box of 20rnds. I wish I would have bought a 243, cheaper ammo, more fun to shoot and gets the job done. Using the best bullet for each gun, by best I am guessing the one that shoots the best out of all other brands/grains. A 7mm wby mag has a muzzle velo of 3070 and a muzzle energy of 3662.
300 mag, has a mv of 2905 and a me of 4122. But after 500 yards teh 7mm is still holding strong with Mz energy and the 300 has dropped drastically. either way, both will kill deer.