I can’t figure out what typeface it is

This is not a typeface (note that it is right-reading). I assume that individual molds of characters where assembled into whatever wording was needed and then these were incorporated into the final mold for a machine part so that the lettering would show up when the part was finally cast.

The P, B and R have some style and whoever made the molds probably copied some existing typeface to the best of their ability.

I would guess op has flipped the image for our viewing comfort

If the image is flipped and it is cast (Typefoundry) Printers Type, than the cast Body would all be the same size, even in a blurred Pic like this one, you can see the Body is slightly off, but - it’s not just us Printers who use type, a whole Marking Industry is out there to offer wares, the surfaces are slightly rounded and it looks quite used, but it could have been used to be impress anything, not just what we do.