I recently purchased a FX wildcat 22 caliber and along with that I got a Hawke Vantage scope. Which I love the both of them but the problem I seem to be having is the scope is always losing zero. I can be shooting it one day and put it down and come back the next day and it's shooting low and to the right pick it up the next day and Its high and to the left. I had to shim the rear mount because it ran out of elevation. I'm currently using a set of BKL High rings. Any idea what's causing this thing to be so erratic? Could I have a bad scope?