I have a pre-ban Dragunov and I went to clean the bore and ran into some trouble.I cleaned from the muzzle end because cleaning through the breech would actually bend my rod.Does this weapon have to be cleaned through the muzzle?Also I had to push pretty hard to get the patches started and more than once I contacted the muzzle crown.I saw a scrape on the brass end.I am using a Dewey rod that is coated with brass fixtures at the end.I the brass hard enough to damage the crown?Help!