The single Dickson is number 2820, and using Nigel Brown's book would put it around 1867, which is incorrect. John Dickson & Son informed me that Dickson's built their actions in batches and shelved them to get the build economy when a customer walked in and ordered something obscure. The serial number 2820 was from an earlier batch of actions and therefore out of sync with the the rest of the 1875-dated guns.

I'm told Charles Gordon ordered twelve 12-bore pinfires and two 32-bore pinfire pistols from Dickson's. Thanks in advance for checking the number, Lagopus, I don't have that book.