Ron -

I was gonna stay out of this one but the stamp on what you identify as a Hieser (HKL to me for clarity) in the first photo, and the stamp in the third photo that you identify as a Johnson BB bear an uncanny resemblance. In fact, aside from the errant 7, the 3 is a serif on both sheaths. Neither jibe with the identified Baby Dot in photo 2.

I think this shows that Maurice apparently had the older style serif stamps as I have maintained. The rule of thumb is the shop did not stamp sheaths, so that is another debate. While it is apparent they were not used much, the Johnson sheaths with this stamp do exist. I do not know if he changed to a more modern font in an effort to distance himself from HKL as an impetus for the change.