In the traditional muzzle loading crowd these are called "swivel breeches". Custom made repros of these were somewhat popular in the historical trekking crowd in the 1990s. Two trekkers in my group had them back then. Admittedly I'm not been an active flintlock shooter or trekker for 20 years or so, but I've not seen many lately as compared to back then.

Last edited by Chasseur d'ours; 02/15/13 04:57 PM.