So I decide for the first time to field strip my Ruger Mark II (.22LR) pistol for a good cleaning. I found that removing the barrel/receiver from the frame required what I believe to be an unusually great amount of force. I've attempted to reassemble the barrel/receiver to the frame but I am unable to do so without again using allot of force. I am guessing that this isn't right. Has anyone else had this problem and found a fix for it? I can't find any burrs that might create interference during assembly and I don't want to start filing or removing metal without knowing where the problem is. Any suggestions???