@--dante-- I've never had one with a regular stem but
@condorlover1 has one. I've got some Markus Fohr clay pipes and they smoke very well but tend to become more heavily stained with smoking than English clay pipes...
32 minutes is the best smoking time with my clay without relighting!
I still don't know how Cavendish at Bolsover Castle made his clay pipe of baccy last more than an hour; I couldn't make mine last that long!
After my long slow smoulder in the churchyard there was still a bit of unburned tobacco left in the clay bowl - does this mean that something is wrong???