25.06 might be great with a 24-26" barrel, but this is why
I'd rather go with a 270win with a 22" barrel, give me a shorter, stiffer barrel, that's my current thinking these days.
you mentioned 6mm., I always thought a 6mm Rem.AI would be quite awesome! and with a 24" barrel, I bet it could probably match the 25.06 or come close and wither higher BC's.
or maybe a 6.5-06?
Let us know how it turns out...