I noticed these comments in another thread, and wanted to start a slightly deeper discussion without diverting the original thread.
http://badgerandblade.com/vb/showthr...ed-Tip-Handles I got the idea that the '+' and 'o' were introduced around 1957. My guess is that this change helped the ladies and gents in the factory find the right baseplates for the red, blue, and standard super speeds. So I would expect a pre-1957 red tip to have no plus sign on the baseplate, and 1957 or later to have the extra symbol. My own C-1 and E-1 both have the plus sign, but C-1 might have been mixed production.
Does anyone have a C-2 or later red tip without the plus symbol?
Later on, probably C-4 or D-1, the handle design changed slightly. The crimp went lower, the retaining mechanism changed, the hole at the bottom of the knob grew 1-mm, and the razor weight dropped by about 2-g.
Here is a table to summarize what I think happened. If you have additional information or contradictory evidence, this would be a great place to discuss it.
Date Code Plus Symbol? Retainer Knob Hole ID (mm) Weight (g) Notes A-1? no cross-head, high crimp 6 66 First production. Achim has an A-4. C-1 yes cross-head, high crimp 6 66 Baseplate symbol added, probably to reduce factory errors. D-1? yes ring, low crimp 7 64 First production. Achim has an A-4.