Treblig,
R. Gordon Cumming was in Africa during the mid 1840's. His Dickson was a BIG rifle; I believe a 6 bore 2-groove double. Much better for elephant than his Moore and Purdey 16 bores which he was forced to use once he "lost" the Dickson due to a barrel blowing up. It would be great to find its specs in the ledgers, but it may have been made for someone else and he bought it used before his trip. Still, there could not be too many rifles like it made.

I believe I have his Purdey 16 which he also bought used. He took it to India when he went there with the military in the 1830's It was built in 1832, From counting listed rifles in Unsworth, the 10th double rifle Purdey made.

Best and Happy New Year!

Mal