Whats long range? The answer lies in the shooters own definition.

If its 300yds, then anything in the 25/06, 270, 280, 30/06 etc range will do.
If its 400yds, then anything in the 264mag, 270WbyMag, 7mmMags, WSMs, 300mags will suffice.
If its 500+yds then look into the "super mags" like the 7mm/300 UltraMags, 30-378Wby, 308 Lazzeroni Warbird (my personal choice) etc...

Now before anyone says, "But I kill deer @ 7000yds with my 270" I offer the chart as a "take what shot your offered" solution. I dont wait for deer to stand still and pose perfectly broadside. Sometimes you gotta reach the heart via the rear end (aka Texas heartshot) or you gotta drive deep through the chest diagonally. Any of the cartridges at any of the ranges mentioned will do that. But the higher and farther up the chart you go the more expense, recoil, blast and "special situations" you must deal with.

Nothing is perfect (tho I suppose a 24" 300WSM of about 6#s with a quality 4x12+ scope is about as "all around" as I can think of!)
RA