Not to insult your intellegence.
I am a boiler guy and we go for the easy answer first every time.
With the rifle and scope combo are you sure everything is tight?
I once went out to a range where a guy was trying to sight in his deer rifle and he had the scope LOOSE in the mounts.
Yea Loose and he was going to tighten down the mounts and the scope when he had the rifle on target.
Don't ask me
I think he was confussed with bore sighting, mounting a scope and sighting it in.
But could you have a loose mount? Loose rings? and finally a loose scope? Is everything tight and did you use any anareoic adheasive? (lock tight, siper glue, Ect...)
the next thing I would look at is the scope. is there something broken inside the scope?
Does the gun have iron sights? Can you shoot the gun and see what kind of accuracy you are getting with out using the scope.
Put the gun in a rest or gun vice and sight along the barrel and see how the gun works. If not using the scope you get a group then it is the mounts, the rings, or the scope.
Can you move the scope? Do you see makes where the scope has moved either to the rear or the front since you mounted it? Yes- Loose scope the rings are too big.
hope this helps.