My VL&D/Sauer 12ga from around 1901 is marked 13/1 om both bbls. I have not actually checked them but they should run to at least .719" This is about a 7lb gun with 2 3/4" chambers marked 70 on the extractor face.
I have a W Richards (neither William or Westley) hammer 12ga whose bbls are marked 14. It predates chamber marks but has been 12ga for many years at least. It came to me via family & due to its condition I have never shot it, but know for a fact that in spite of its short chambers & twist bbls it has digested a goodly number of 2 3/4" "High Brass" 4s.
