I have seen photos of 19th century French doubles chambered for 7.5, 8.0, and 8.5. Journee notes that at the time there where shotguns (gauge not mentioned) chambered up to 9.0 cm (4 1/2").

16 gauge French gun from pre 1900 chambered for 8.0 (3 1/2").
https://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=516435&page=1
Didier-Drevet barrel, 16 gauge which looks to be chambered for 8.0. It is double proofed in Saint-Etienne for PS powder so it is pre-1900 and it does not have the 1900 prize marked on DD barrels but rather 1855, the date of his original gold medal at the Paris Universelle. Barrel is Damascus. It is post 1889 since chamber is marked in cm. (The barrel oddly is not dated or I cant read it.

Last edited by Argo44; 05/10/20 08:39 PM.
Baluch are not Brahui, Brahui are Baluch