You are loading, load for the weapon.
Same brass, same primers, same powder, same bullets, same head holder, same dies, same....
Different amount of freebore (5.56 is longer), different method of measuring pressures.
Longer (heavier) bullets will need a tighter twist to stabilize.
Just prep the brass the same and start with a beginning load for your selected powder. Work up in powder charge till you find what the weapon likes. Watch for pressure signs and keep a record. Also, check each step, before doing great numbers, to make certain that the cases will chamber properly.
Seldom will the best accuracy be found at the max/heaviest loadings.
Enjoy and be safe,