I have a brand new Savage Mark II with factory-installed Weaver scope. I could not zero the rifle right from the get-go. A few rounds would land on top of each other or millimeters apart and then without any scope adjustment the next few rounds would land in a completely different spot on the target but still in a tight grouping. What do you suspect the issue is? Riflescope rings? But if the rings than I'd think that every shot would feel errant. I'd be grateful for more experienced shooters sharing their expertise. Thanks!