Ultimately the top importance is what you shoot best, but with all else being equal, loading to the same relative recoil/power/etc, is it more economical to buy, say a 147 grn 9mm bullet at $80 per 1,000 and load 4.0 grains of powder or buy 115 grn 9mm bullets at $70/1,000 and use 6.0 grains of...