I would second WBM's suggestion to get the 1:8 twist. I have a Shaw 1:8 twist barrel that is accurate, (when I do my part) out to over 1000 yards with no difficulty. i have not shot it in a while, but I think that was with 140 A-Maxes. Rule of thumb for me is to go with faster, versus slower twist barrels, although I understand that there are situations when a slower twist may be more appropriate.