Nice one! Mine has a whole lot of rust on it but very similar to yours.
There is a way to determine the mfr. of these early turtles...after collecting them for so many years I noticed differences in the way the rim joint is welded/spot welded and other signs. With the helmet stamps that were readable I have deduced that:
BMB - these are normally stamped vertical to the rim and if conditions are right, you should be able to feel a slight bump on the outside rear skirt of the helmet...opposite the stamp. BMB stamps always seem to be heavier on one side of the stamp which produces the opposing bump. So far every BMB I have owned has had this feature. The rim joint is also welded closed.
F&L - The lug rivets on these always seem to be larger than other makes. The stamp is usually very light and not in the place you would think...so far every F&L stamp I've found is in front of the chinstrap lugs. The rim seam is not welded closed but it is overlapped and can have up to four spot welds.
RO&Co. - The stamp is normally parallel to the rim and stamped lightly. Rim joint is not welded closed...usually a small space between ends...and can have up to four spot welds.
...of course these observations are from all the MkIII's I've studied, but I have noticed the same characteristics on the MkIV's as well.
Last edited by mk1rceme on Wed Oct 26, 2011 9:19 pm; edited 1 time in total