I agree with all above. Im not tech savy as NM, but my RRA custom with Bart Baldwin custom 20" heavy barrels and brakes in 8,9 and 10 twist all shooting Horn V-Max 50-55grn both flat base and boattail in the neighbor hood of 3255-3400fps and just .05-.010 off the lands all produce groups sub 1 moa to sub 1/2" moa all day. And as RR and NM said, the SD really makes the bullet perform to optimal performance.
I have ran upto the 69-73grn bullet range, but just have not found the reason to for the added cost and extra consideration of the loading needed when I can just grab my dies set for 55 V-Max and stomp'em out with out a thought. Coyotes never seemed to notice the difference!!!!