"And what process did you use for the steel finishing?"
Draw file, 120 grit paper, burgandy sctochbrite, then ... gasp!, Brownells Oxpho ....cold blue Applied with steel wool and kitchen scotchbrite.
I know, not traditional for this type of thing. However, it comes out dark and even and it is pretty durable. I told my friend if the finish does not hold up, or he just does not like it, I'll brown the barrel for free. In the low humidity out here traditional browning is not easy to do right. I normally end up using BC hot brown. It is challenging to make it come out even.