Mike- you'll probably need to try both bullet weights to find which works for your rifle. If you're going to shoot factory loads you'll find some that work, some that are horrible. I shoot two ARs with 1/9 barrels, both are most accurate with the 55s.For factory loads Black Hills soft point will shoot better than I can, all day inside an inch. For my reloads the best is Sierra #1365 boat tail soft point - these can do 1/2 inch at 100 yds. These aren't bench rest rifles with monster scopes, these are just 3gun rifles. I hope this helps. Oh, the worst I've ever had is PMC- 4+" at 100yds.