Little is truly custom in our game. Actions certainly aren’t custom, they are named models that are precisely machined in a “factory” with minimal handwork to hopefully be exactly the same, one to another. If they weren’t the same, then you couldn’t order up a chambered barrel, which all the smiths can and do fill, based on specs. It would be pointless and frustrating to have more than one of them. Items that are produced exactly alike are the opposite of “custom.”
A stack of barrels made to a “spec” before a customer has ordered them isn’t in any way problematic to me, if the barrels are good. We rely on specs all the time on parts with tighter tolerances and greater costs. Most “f-open” barrels don’t even have a contour, we call them custom anyhow but they are cut bar stock, plain cylinders, that have no front or rear. They are drilled and rifled, usually tracing a giant screw’s twist, with nothing attached, indexed, tapped, planed, threaded, or coated onto them; definitely not custom to a particular gun, with the only non-automated decision having been made, being when to stop lapping them.
My powder, brass, primers and bullets better not be custom. I don’t think getting right a shouldered pre-threaded barrel’s head-spacing is necessarily harder than other tolerances the action is not provided for. A trigger’s 100% reliable sear engagement with cocking pieces is the most important function of a gun but I haven’t had any difficulty interchanging unmodified pre-made bolts, triggers, hangers, etc. Many bolt upgrades and different faces from inventory across brands manage perfect integration as well.
