I bought my son a Marlin 60 recently and picked out a Nikon Prostaff 3-9 Rimfire BDC scope. Trouble is I'm having a hard time siting it in. My groups are hitting 7-8 inches low at 50 yards. Simple, just turn the elevation turret up, right? The issue is it's already all the way up. Seems I have no more adjustment. How can this be? The only solution I can think of is a different mount (currently using low profile rings). I mean, I've heard of mounts that are canted downward, but isn't that for guys shooting long distance? I can't understand why a 22 would need that at 50 yards. Any ideas?