Indian Joe - I agree it's an easy fixed - I have re-breeched a number of barrels over the years . Just a mystery as to why anyone would go to the trouble to mill the slot - not a brilliant move to do it on the underside if intended to "de-mil" the piece and not mark it somewhere so someone would know. But who knows? Conjurs up the scheme of an angry wife who has her machines lover do the work so her husband get's a "fatal surprise the next time he goes shooting!