shieldbearer428,If it is the kind with the flip clamp,it needs to be slid on from the rear,you must remove the flip clamp and loosen the tension screw,tap on the mount with a rubber mallet or wood from the back to front position,put the clamp back on and flip it tight to the front.Look closely to see the ridges align with the jaw of the mount and tap it forward until it seats and is aligned properly. I assume its the same with the 3 or 4 screw kind. hope this helps.