IIRC the grooved forearm was only used on the earlier ones. The 67 came out in 1934 and was made until 1963. Off the top of my head I think the 67A appeared in the late 30's (?). I've seen a couple articles on them in gun magazines that I have someplace in a stack of magazines that I've saved. If you google Winchester Model 67, Wikipedia has a nice run -down on them including stuff like what was changed when. They're sweet little guns and mine is also the best thing I have for using 22 shorts.
