Flush with gun cleaning solvent. Apply very light viscosity oil. That would be the course of correction IF the end of crossbolt projects proud of the exterior of breech ball after closing (cross bolt isn't fully seating in the piercing in extension). However, this bit about the rib extension[?] hitting the cross bolt on closing suggests that the bolt is not being held in an open (retracted) position after opening and you are pushing the lever to the right on closing to avoid the interference. The top lever spindle has an arm or lever which operates in a slot in the cross bolt to actuate withdrawal. When the end of the arm wears, the cross bolt sometimes won't fully retract to clear the extension. I've had that happen with a no-name Brum action; the solution for me was to apply pressure under forearm (manually closing gun tighter) while operating lever to retract the bolt on opening. That appears to give a tiny bit more bolt retraction and gun opens fine. Your gun appears to exhibit the same symptom at a larger scale. Is there a burr on the X-bolt created by the interference with extension on closing? Could the bolt possibly be bent and binding in its recess in the breechwall?
jack
