What is the correct angle for the engagement surfaces of the locking block and the locking surfaces of the rear lugs on the barrels? I would assume they are equal and the block moves forward with wear as the top lever gets closer to the center. Next question, how many thousands of an inch of wear does it take to get to the center requiring a rebuild? If the gun locks tight does it really matter where the top lever stops? Thanks in advance for the Perazzi pro's advice on here.