My brother and me were just discussing these two cartridges/calibers. We both have .30-06 as our first choice. The 06 is so versatile. If you are only going to have one center fire rifle the 06 is a sound choice.
In my reloading books I look up the cartridges.
.257 has loads for 110 grain bullets from 2800 to 3300 fps, with bullets having a ballistic coefficient (BC) of .39
the .30-06 has loads for 110 grain bullets from 2900 to 3400 fps, with BC of .25 and .29
Since I have actually wrote the code for the ballistics calculator in Gun Log, let me illustrate the significance of the BC.
.257 Weather Mag
300 Yard Zero, MV 3000 fps
400 yards, -11.3 inches, Velocity 2091
500 yards, -30.5 inches, Velocity 1891
.30-06
300 Yard Zero, MV 3000 fps
400 yards, -14.9 inches, Velocity 1664
500 yards, -42.5 inches, Velocity 1411
Notice how the BC really effects the values the further the bullet travels.
Now, don't take it that the 06 at 500 yards is something under powered, it is just in this example that a 110 grain bullet in .308 caliber is not "shaped as good" as the .257.
The BC on the 120 grain .257 is the same as the 110 grain, so the values above wouldn't change, only the energy (which I didn't calculate).
Now take the .30-06 and let's pick a bullet that has a good BC. Hmm, the 150 grain A-MAX has a BC of .435. It doesn't show a load up to 3000 fps, but one for 2950.
Let's look at that:
300 Yard Zero, MV 2950 fps
400 yards, -11.1 inches, Velocity 2089
500 yards, -29.9 inches, Velocity 1953
Let's put those side by side:
Code:
.257 Weather Mag .30-06
300 Yard Zero, MV 3000 fps 300 Yard Zero, MV 2950 fps
400 yards, -11.3 inches, V 2091 400 yards, -11.1 inches, V 2089
500 yards, -30.5 inches, V 1891 500 yards, -29.9 inches, V 1953
This shows that the lowly .30-06 is an amazing cartridge. It isn't the hollywood starlet of cartridges, it is the leading man. ;-)
I have a .30-06. I would like to have a .257 Weatherby Magnum just because it is what it is.