Been a while since I checked out this thread. Dave, those are great pipes! Aren't many post-1920s hallmarked BBB's out there, and that's ^^^ a great one.
I added another BBB to the collection a few months back. This one has an amber "Glokar" stem. The Glokar was BBB's version of the P-lip, except instead of a round hole, it has a little, rectangular slot. Glokar stems aren't common, but I wouldn't call them rare, either. However, I've only ever seen one or two other Glokar stems in amber. And this one has only been smoked once or twice, if that.