In a Vanguard it would be quite safe to load the 30-06 to 270 pressure.
I agree and the difficulty is knowing the relative pressures of the various 30-06 and 270 loads. Testing 5 factory 165 gr 30-06 loads had pressures ranging from 47,000 psi to 61,700, with those velocities being 2717 fps and 2849.
The interesting thing about handloading is that every component (bullets, brass, powder and primer) has a not inconsequential amount of variance. My experience is that by the time we see the "normal" pressure signs (sticky extraction, blown primers, etc.) we are way over SAMMI pressures. I have a 30-06 case that experienced 73,000 psi and it looks just like one that experienced 55,000 psi. in the same rifle.
