I have made lots of 270 Winchester brass from 30-06 Springfield brass and had zero problems. Yes a little shorter, but no damaging effects from such modification. Just lube and run through a full length sizer die.
Some don't like mixed head stamps, but I have had no mishaps. I properly label my ammo/brass and I am the only one who has access.
I also make 7mm-08 Remington from 308 Winchester, 338-06 A-Square from 30-06 Springfield. I also like the use the cheapest brass available or use whats on hand.
yooper77