grout-scout, I misread the 6" MPBR for the 7mm-08 when I posted yesterday. The MPBR for the 7mm-08 is 284 yards (not the 250 yards I wrote yesterday) but the bullet is falling fast out there and it drops another 1.4" by the 300 yard line.
Using Hornady Interbond bullets for all three calibers I looked for the "midrange rainbow trajectory" and it really doesn't exist. The trajectories of all three calibers are within 0.6" of each other out to 200 yards and still are of no real significance in hunting at 250 yards.
For the .300 WSM I used a 150 grain Interbond at 3300 FPS, for the .270 I used a 130 grain Interbond at 3150 FPS and for the 7mm-08 I used a 139 grain Interbond at 2860 FPS. I used a scope center line of +1.5" from the bore and a 6" MPBR to keep the bullet no more than 3" above or below the line of sight. That was intended to allow a center hold on the heart/lung area and to not need to apply any hold over.
At 250 yards the .300 is +1.1" of the line of sight, the .270 is +0.7" and the 7mm-08 is -0.5". I know some folks might make a big deal of the 1.6" difference from the .300 to the 7mm but it really does not matter. No big game animal will know the difference between a bullet hitting an inch above or a half an inch below the middle of his lungs. Use a center hold on the heart/lung area and you'll put your game on the meat pole.
Only at 300 yards is there any difference and it is likely still smaller than most folks would guess. At 300 yards the .300 is at -1.6", the .270 is at -2.3" and the 7mm-08 is at -4.4".
With a 10 MPH wind directly from the side of the gun-target line there is less than a half inch difference in the 300 yard wind drift-so much for the often claimed wind bucking ability of faster cartridges.... All three loads fall in the 6.2" to 6.7" windage with a 10 MPH crosswind. Clearly, for most hunts reading and reacting to the wind is more important than how flat your bullet flies.
You're the only one who can make an educated guess as to how often you'll need the difference between the 284 yard 6" MPBR of the 7mm and the other two cartridges. The 300 WSM has only a 33 yard MPBR advantage over the 7mm-08 and 14 yards on the 270 Winchester. How often do you soot at deer 300 yards away? Do you feel comfortable favoring a little high with the 7mm-08 at ranges over 250 yards? If so, there is no practical difference that a deer will ever notice between the three cartridges.
All have the power to cleanly take deer at 300 (even 400 yards) provided we as hunters do the most important part-put the bullet where it belongs. As I wrote yesterday, I'd leave the .300 in the safe for deer since it is a lot more recoil and muzzle blast than you need to put up with for deer. Of the other two I'd personally reach for the 7mm-08 but you may be more comfortable and more accurate with one of the three over the others and that may be the best way to choose.
Lance