I had some experience with these there other day. The universal ones are a pain and there cost is expensive. My bud was telling me about these great ones he was using, but i forgot that name. I will get back to you on this, if no one else can help.
I use my nieghbors flower pot its a hunderd yds from my picture window. I just pull the bolt out line the bore up on the flower pot after the rifles secured where it won't move around then adjust scope its usually within a couple inches