I had a rifle built by a friend its a 7mm rem mag using a Stiller action, Bartline barrel, McMillan stock,Jewell trigger. He used a match reamer so he says and has consistently built tack drivers for other people. Well we found a load that works good but I'm getting some wild ES's of 50 and he suggested neck tension. it hasn't mattered at closer distances but everything falls apart past 725 yards. How do I go about getting the most consistent neck tension. I'm using redding dies on a Hollywood press Retumbo and a 168 Berger's 30 off the lands.