Unusual lever boss code . . .

One of my M99 Featherweight’s has a code of 176 . . .NO LETTER!
The chart on this site, listing DoM’s by serial says my rifle was made in 1955.
How come NO LETTER . . .only a 3-digit lever boss code?

Another Featherweight I have DOES have a matching code (11k) to the serial (962xxx), so no problem there.

Appreciate any answers. —Jim

Upon further reasoning, I’m now thinking what I thought was “176” is, in fact, “17G” . . . making the code matching the serial.
Being stamped on the curved surface, makes for poor impressions!