I hear about people's trouble with scopes all the time. With a scope having magnification there is a concern over paralax. Cheek weld and alignment to the scope centerline needs to be the same each shot. There is one range where the paralax is correct, usually 100 yards for a scope intened for centerfire, where one can be off and still hit. With an adustable objective range can be set and that point moved for the range desired. But in a hunting situation one can't always count on that pesky game to be at just the right range. So once again practice is necessary to be able to mount the gun and have the same position on the scope each time.
Fit is important as well: the better the fit the less adjustment the shooter has to do to get the same cheek weld. That is my pet peeve with the shoot through rings. If you can get low enough on them to use the iron sights your cheek will be off the stock when shooting through the scope. I fit my stocks so that I am tight on the cheekbone and in the same spot each time.
I always wonder how many guns have been sold as inacurate when it is more like poorly fit.