I haven't seen any real difference on deer or elk sized animals between a 270 WSM, 7mm Rem Mag or 300 Win Mag with similar if not the same bullets (Nosler Partitions). I have seen elk take the hits a little harder with my Whelen and 338 Win Mag.
Saying that, I picked the 7mm Rem Mag as my first rifle and could've stopped right there and been just fine. Whenever someone asks me about which cartridge they should look at, the 7mm Rem Mag is first. Especially for a non hand loader, a box of 160 Partitions as loaded by Federal is amazing as is the Winchester loaded 160 Accubonds.
I really liked the 7mm's so much I had a 7mm Mashburn made up. Fires 175 PTs the same speed as my 300 Weatherby does the 200 Partition. Lighter recoil and a lighter rifle.
If I could rewind 20 years I'd be just fine with an excellent 7mm Rem built by a great smith that weighed 8lbs loaded. Probably be money ahead in the search for perfect.
