There is one thing that todays ML's seem to share with their ancestors and that is inconsistancy/ lots of variance in bore size of a given cal/bals per lb /gauge or gun in the past a gun of (x balls to the lb) which equaled a .562 ball might have a bore size of .577 thru .623 and be acceptable, todays guns are not quite as varied but seem to retain some of the scope allowed in the past for bore tolerance and still be correct for the Cal.