On some guns -- cheap & expensive -- I'm certain the through lump made the action easier to machine.
I wonder if a big maker like Webley & Scott machined similar rough actions for all their sidelocks and then sent the actions on their way for building -- one would become a 3rd-tier gun, another a Premier? But they all started out the same way. Makes sense.
On other guns, I bet makers used through lumps to enlarge the hook/hinge-pin radius without making the action much deeper (Rigby double rifles).
Last edited by obsessed-with-doubles; 11/06/20 05:12 PM.