I have a nikon monarch 4-16x mounted on a 10-22. When i first mounted it i did not have enough adjustment to even get the gun zeroed at 50yds. It replaced a VX-1 which after zeroing was close to the center of its adjustment range so i dont know what is wrong. Everything is tight. Right now i have a 20moa base on it and have about 18MOA of adjustment to work with. Any ideas on what could be wrong?