Hi I have always fitted my own scopes with no problems i always use locktite 243 on all screws which locks the thread but is fortunately easy to undo. This week i swapped my leupold scope bases from standard to quick release so that i can change scopes easily. Went to the range this morning to make final adjustments, sighted the target through the barrel and adjusted the scope to match. put a round in the chamber closed the bolt pulled the trigger (click) misfire, i waited a while before ejecting the round then noticed that the primer had not been dented, tried it again same result. on the long drive back home i was thinking about the problem, all i had done was change the bases. when i got home i removed the scope and putting my finger in the chamber i could just feel that the rear screw of the front mount was protruding into the chamber preventing the bolt from closing fully. I had used one screw from the standard mount which was about two threads longer. Problem Solved.