Something else you can do is... with the open sights, work your load up at 13 or 25 yards. Then you know the scope is not to blame. If it is shooting basically a very tight group at that distance, then put the scope back on.You now know the load is good. Sometimes, scopes fail. It is just an unfortunate truth. So if you know the load is good, and you put the scope on, then back up to the distance you want (once sighted in) and then try again. See if it is the scope or not. If you know the load is good and then once the scope is added the group falls apart, get a different scope.