I am quite a newbie too,but have learned that the rest is very important in this game.You can have the best rifle in the world,without a good rest you will never see it's full potential.Make sure all is well aligned and stays that way if you pinch the bag.If the rear is off center it will have influence.
Benchrest is a combination of all factors,one thing wrong and you will see results drop.When I started a year ago I was shooting around 230 240,yesterday my card was a 250 18X.
Experiment a bit with ammo,give rws R50 a try,my annie realy loves it.
Remember fiddeling with the rifle is half the fun although it may drive you nuts from time to time.