Another very knowledgeable poster offers the following:
The diamond may be referring to patent #2319 of 1868 by James Purdey for an "adjustable tang-mounted rear sight"
Again from Diggory:
"This patent relates more to the fit than the function of a gun, providing the same adjustment as an elevated rib, a concept which had first been introduced by Joseph Manton in 1806. Many of Purdey’s guns at that time were fitted with either ‘semi-bottom’ or ‘bottom’ ribs. These were set down between the barrels, and in the case of the latter actually exposed the breech-face between the breech-ends. While they allow for a slight reduction in weight, they are obviously virtually invisible to the user when firing. James’ solution, in essence, was to have a plate screwed onto the top tang and over the breech, which could be adjusted up or down by turning a screw. This would only work on a gun that was not fitted with a toplever, as in that case the two would have occupied the same space. However, once again it is not known whether any guns were ever fitted with these devices."
However, I don't see it on this gun.
Last edited by Argo44; 06/22/20 02:12 PM.
