Ausie-guy, I thought you were probably shooting outside, since most places don`t have 50yd. indoor ranges. I thought maybe there was a big shade tree near your 30 yd. shooting station.
Now that you are shooting consistantly right, further right at further distance, it is much more likely that your rest is out of centershot. I bet if you move your rest ever so slightly left, you will see your impact shift back towards the bull.

Good Luck!

NRA,UBP,BASS Member
New Stanton,PA