Pick optimum powder for bullet weight. Then find your pressure with a kiss or as close to it. 70s have long throats so you may get a freebore...
65 -
I double checked today. My 70's throat is 2.715 AS BEST as I could consistently measure. With a 3.000 COAL that is NOT a long jump to lands.
I barely seated a long bullet and THEN closed the bolt and let the riflings seat the bullet. I had a little doubt about doing it the other way...but today I confirmed it.
Jerry