Good story. My understanding is that if a gun was built to another maker's patent, it would either involve purchasing the action in the white from the patent holder, or building it and then having the patent holder inspect the action and grant/apply a patent use number. I've always wondered how this would work in practice, and what payments would be made for such an inspection.

For instance, if Reilly built a gun using Purdey's double-bite snap-action design, would it require Purdey inspecting the action for the approval, and presumably the added royalty/inspection cost would ultimately be paid by the Reilly client? I'm also presuming that a Reilly-built Purdey-patent gun would be cheaper than buying the same pattern gun from Purdey's.

I can see how having a desirable patent could earn the holder good money, and this fuelled the rush of breech-loader designs in the 1850s and 1860s in particular.