I'm trying to set up a gun for a friend and I need a little help. It's a Rem 700 with a 28" Snieder tube in 300 ultra. He has a 4.5x14 leupold with target turrets. I'm thinking Burris high rings with off set inserts. He wants to shoot 1000 maybe 1500 but still be able to come back zero at 300. If this is possible what inserts will we need (.005,.010, or.020)? And will it be just one ring or both? How much difference does each equal at 1000yrds? Thanks for the help.