Quote Originally Posted by hwjhfs View Post
Two things come to mind for B.P.: Black Powder and Base Pin. In 1896 I do not believe that Colt would have referred to the earlier frames as "Black Powder" as we do today. So, i suspect the B.P. was for Base Pin. Since the transition from screw in retainer to the spring loaded retainer was began in that time frame a customer wanted the new type of release/catch and to be sure he got it instead of the screw in frame type he requested it.
Makes sense B. P. catch for Base Pin catch, or like StClair said B.P. for Button Push catch for base pin. Hopefully Paul will be able to shed light on this. But right now I lean toward it having to do with the new style base pin release/catch.