Terry, I have the proof tables going back to 1855. They were changed in 1868, and again in 1887. No new tables came into being in 1875, and the fractions were not used in the 1868 tables. The fractions first appear in the 1887 tables.
From Baron Engelhardt's article, "Proof in Great Britain", under "Rules and Regulations of 1887":
"In all smoothbore and choke-bored barrels, from 4 to 10 bore inclusive, the bore size was divided into three parts and marked accordingly . . . from 11 bore to 17 bore inclusive, the bores were divided into 2 parts; thus the division of a 12 bore was 12 and 12/1."
I think most people accept Baron Engelhardt as perhaps the leading expert on gun proof, at least up through the rules of 1925.
Last edited by L. Brown; 10/31/12 09:21 AM.
