Beginning of hooded front sights on Mauser 1940

[runner]

Wondering what is the earliest noted code 42, 1940 dated Mauser with a sight base slotted for a hood ? Vol lla pictures a qq suffix and notes it is "early". Their is a mm suffix in the pic stickies that looks like a factory cut to me. Asking because I have a oo suffix cut for a hood, it looks factory, and does not show any signs of having been in a depot.

 

[bruce98k]

That 'qq' block is in my collection and is factory slotted. I know of others late in 1940 but not sure of serial number range.
The change was not consistent as I have a byf41 'a' block that is not slotted.