Edit:I have seen some Tyro stocked versions Stamped HW55T while other others have a different designation such as M or S. Does it mean the stocks have been swapped out at some point?
From the gallery and the catalog clip, the checkering on the sides of the MM forend is in the early '60's style, but there is no checkering on the bottom of the forend, like the top gun in Mike's photo has. There is a rail, instead.
Dave, the two pics below show the basic checkering patterns on the 55M/MM. My strictly unoffiical terms are “W” and “square” patterns, LOL.Early 55’s seem to always have some variation of the W pattern, but in the model’s real heyday of the 70’s and 80’s, it seems to go back and forth between the patterns - there was no point where one changed permanently to the other. No doubt there were two different subcontractors who made the stocks in small batches.In my observation, the square pattern covers more area and is a little more finely done, maybe 18 lines-per-inch, vs. 16 LPI for the W pattern. But all HW 55’s are pretty!
Thanks for those photos! I've probably overlooked it, but I don't recall seeing the square pattern with checkering on the underside instead of the rail before. Nice! I thought the MM might be the Match Meister; but apparently it's the Mystery Match.