Mine has the London proof marks from 1868-1875, but then also has the 12c in diamond and choke mark of a later proof.

https://i.imgur.com/YLwoEDU.jpg

Each barrel also marked with a capital A and also this mark:

https://i.imgur.com/dUpPF3w.jp

Last edited by Ploughjogger; 03/20/23 08:15 AM.