Ok mate, had you cleaned it prior to missing the roe? Then when you got it "spot on" did you clean it again? What I am getting at mate is that some rifles wont shoot to point of aim clean, and need several rounds down them to foul the rifling with copper, then come back to zero, It might be worth taking it out, shooting a group you are happy with, then take it home, do not clean it, then take it out again and see if it shoots to point of aim again, the fact that you say it was spot on suggests that the crown is ok or it would not zero at all, if you have eliminated all the above, then the logi