I agree with MD54 - Play with the loads, bullets, sabots until you find the perfect combination for your rifle. If your scope is mounted correctly, all screws tight (don't over tighten) that rifle should easily shoot within an inch at 50 yds. At 100 yds. everything is magnified by either your mistakes or the load combo.
Also, make sure you are not resting the barrel on the rest. Only the forearm. Not sure what you are doing - just an idea.