The following lines were added (+) and removed (-):
Timeline1894 - First production year1924 - renamed Model 55 -w- 24" round barrel & shotgun-style butt plate1932 - renamed back to Model 941933 - Model 64 variation introduces 1933-19571965 - revised less expensive manufacture1972 - bluing and finish improvements1982 - angular shell case ejection199x - change from half-cock notch safety to cross-bolt safetyxxxx - change from cross-bolt to tang-mounted safety