The lever must swing into a fully locked possition for the hammer to get back far enough to find full cock notch if im seeing the right lock works in my head. Take a small piece of play dow and put it on the barrel locking lug, carefully close the gun, holding the lever back and then let it down to lock the gun barrel easy. open and see how much of the play dow squezed back into the lug recess. If the locking lug isnt crushing the playdow and grabing enough barrel lug, something is stoping the lock up from happening.