It is my understanding that at the time 9BC was discontinued (about 1969) there was a period with either one and they started making XL 90 shape in 70s??? I do not remember exactly so take it with grain of salt. My 9BC Deluxe is from 40s..
There is another 9BC Shamrock on ebay for 575$ buy now...Seriously-Are them people nuts?I just bough one last year at the pipe show for 40$.Yeah I had to pay 12$ to clean it but it is a hell of a pipe without any fill.
This new cobble rustication looks like the old one on my vintage 1979 Donegal rocky with silver ring..I do not have a picture at this moment but it looks almost similar
I HAVE a very few pipes with 9mm filter.like 6 out of 150...I remove it after smoking and reuse it after it dries the next day..I only use each filter twice.few pipes I converted to non filter adapters