I had a Criterion Barrel from Jim Briggs chambered in .308, 1-11 twist, freebore 0.90. This thing shoots 175-178 bullets verygood. I would like to shoot the 185 Berger LRBT for 1000 yards and down to a 155 class bullet for 600 yards. What freebore can I get away with, if possible, and not be...