When necking down just make sure that your neck diameter isn't too thick for your chamber and you'll be fine. You probably don't have to worry about that if you use 270 Win or 280 Rem brass to form into 6.5-06, and you don't have to worry if you start with 25-06 brass and neck up.
I don't have any pet loads to give you, as I passed on a 6.5-06 a few years back at a gunshow. But you can find data all over the internet on that round.
Machine guns are awesome until you have to carry one.