The basic difference is that you can push a 117 grain or 120 grain bullet in the .25-06 to about the same velocity as a 100 grain bullet in the .257 Roberts.
Especially in the AI version..
For overall use, however, on deer-sized game the .257 is plenty adequate.
That. I recall that the original Roberts rounds were pretty anemic - 117gr bullets limited to something around 2400 fps.. I don't remember why it was done at the time.. Modern ammo and books show 117s at more like 3000 or a hair over... (24" barrel)..
I have a M70 FWT in .257 that I dearly love.. It's just so comfortable to shoot and to carry.. It would be one of the very last rifles I'd sell.
