Here's a few of mine:
Peterson Pub Pipe with 22.5mmx51.5mm chamber:
View attachment 370059
Unlabeled (believed to be a Cellini Original) Hungarian with 20mmx50mm chamber
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Barontini 1/2 Spigot 20mmx52mm chamber:
View attachment 370061
Barontini Gran Duc 203 (below 1/2 spigot) 20mmx55mm chamber (my largest)
View attachment 370063
I'm including this Erica (Peterson Second) which I believe is a second of a Hand Made. While the chamber is only 22mmx42mm - the bowl is 60mm so theoretically I could drill another 9mm down and still have 9mm at base. The bowl should have been 63mm average but I believe they hit a pit and cut off 3mm and didn't finish the pipe drilling. Its my favorite pipe of all my pipes and really the only one I would need. It came with an orific bit too:
View attachment 370062
Butz-Choquin Fait Main Calabash Extra Junior 22mmx50.5mm - This pipe has thin walls and gets hot unless sipped super slowly which is a common complaint of this pipe.
View attachment 370070
I also have a Comoy London Pride 215 with a 20mmx52mm chamber but I don't have a picture of it handy.