Dustin sent a photo a while back of a coated gun, and the thing looked like it had been hot blued in the picture. Fantastic work. The sad truth is, run of the mill boxlocks are approaching zero demand, and if a guy has one and wants to use it, I shouldn’t care too much about what finish he wants to put on it.
Hey, the queen is dead.
Maybe reach out to Dustin (LeFusil, here) to pick his brain about the gun and the process that was used.
The other thing to keep in mind is that the solder joints on a shotgun barrel eventually need maintenance. It is a regular part of ownership, it just happens. If you are close to that point, your spiffy new finish might be ruined by the ribs needing to be re-layed.
Good luck.
Best,
Ted