Dear Members, I am sorry if this question has been made before, and if this is the case, please redirect me to the pertinent thread or post. I have two Montblancs 149: (i) a late 80's (Germany in the clip) with an F pen that weighs around 31 g with a plastic piston mechanism and; (ii) an older one, possibly 70's or 80's (W-Germany in the clip) that weighs 37 g and has a BB pen and a metal piston mechanism. Both weights include the cap. Does someone could tell me if this 6 g difference in total weight are expected? Thanks!