I pick the 7mm RM Its really close though almost a dead heat.
#'s to back it up:
Muzzle vel. @ 0yrd:
7mm @ 140 gr 3145
.300 @ 150gr 3245
Muz. ener.@ 0yrd
7mm 3075
.300 3506
Same bullet gr.@ max range for Elk 460-465yrd
7mm vel.2197 ener. 1500
.300 vel.2122 ener.1500
It's pretty close. The 7mm has a longer effective range by 60yrd, on the other hand the .300 knockdown power @ longest effective range of 515 is a mile better than the 7mm. The bullet drop for these calibers is identical @ 4-5-600 yrds. The recoil difference is nominal, the 7mm is 1.97secxlb, the 300 2.16secxlb.
Now mind that these numbers are for elk hunting in particular.
Found this info in " The Target Book For North American Big Game" by Charlie Middleton/ Pat Moran. This book is very good, has a lot of ballistic info for almost all caliber rifles. Also shows bullet drop and target impact. Great resource if you cant make up your mind. You can look at the #'s side by side