Theres nothing out there on the web to help really. The top pipe has a corncob shank which will date it earlier than the 1980's for sure. The middle shape with the diamond shank also ceased production by the 1980's. The aluminum shanked pipe is a new one for me, never seen one. The "experimental period" at MM seemed to revolve around the 1930's-1950's when they were competing against a dozen or more companies and had to come out with newer designs. This pipe doesn't look like its that early, but the top two could be as early as the 1950's based on the stems and shapes.
So thats the best range I could give you, say 1955-1985. My guess is somewhere around the mid 60's.