You didn't say which Nikon P-Series scope you are going to get. It is my feeling that your BUIS system will not fir under this scope. Especially if you have your old 4X scope mounted in their triple threat mount which gives significantly more scope clearance then normal rings. Post a pic when you get it installed either way showing if does or does not fit. Many gut's want to keep their BUIS on their rifle and finding a mount that will work can be difficult and expensive, especially if you go with a QD mount which only makes sense.
Nikon Pro Staff