Revic BR4, I'd avoid the ones where you just pick a pre installed load that's close, the Revic or older G7 models you enter all of your info into them. I have the 2nd gen G7 BR2500 it provides a ballistic calculation to 1400 yards the new Revic will provide a ballistic calculation to almost 2000 yards, they range farther but the ballistic capabilities are less.