I have had trouble with scopes before. In one case a scope moved in the rings. The gun smith dealt with that, and also advised me to put a drop of nail polish on the front of the scope ring edge and on the back of the scope ring edge. If the scope moves in any back/front direction, one of those nail polish dots is going to be disturbed, providing immediate indication. I can tell you that this simple technique provides a lot of confidence -- I know my scope hasn't moved it the rings -- which might be nice if you dropped your rifle or otherwise banged stuff up in the field. I now have those front and aft drops on every scoped rifle I own. Minor to no cosmetic defect to that in my view.
I have found that different ammunition can shoot significantly different in my rifles. Also, I shot three or four different commercial loadings and bullet weights until my .25-06 started shooting reasonably well. Try a lot of different available ammo. Also, if you reload you can use fire formed cartridge cases and improve by reloading specifically for your rifle -- finding a bullet/powder combination that suits the peculiar resonant frequencies of your rifle.
