I shoot a Black Diamond and was getting solid one inch groups at 100 yds. The last time out at the range I started getting verticle inconsistency, no problems left and right. I would adjust the scope back to where I wanted it and get no more than two shots before it would wander either up or down most of the time it wanders up. I use 100 grains of pyrodex p and a 250 grain shockwave. I checked the scope and everything is tight. I believe the problem is the scope but I am open to suggestions. One other thing it appears the verticle adjustment has to be moved more clicks than it should have to to bring the rifle back to zero. All my sighting in is done off a concrete bench and solid rest. All replies will be appreciated.