I have a 257 AI ( Roberts with a 40 degree shoulder) that gets close to 25-06 speed .
I built it out of a FN action
23" E R Shaw barrel

I shoots sub inch with about any load with me shooting ,others have sub 1/2" groups with it .

I would recomend the AI over the standard 257 Roberts .
You can shoot factory 257 Roberts ammo in a pinch or to fire form ,I varmit hunt with Hornady 75 gr V max to fire form new cases.
You get all but about 100 fps of the 25-06 but with about 6 grains less powder.

I hate to admit it but if you don"t reload the 25-06 would be a better choice

Either will work great when you find a good shooting load.

Johnch