I did a few brown finishes on cva mzl kit guns, never blue. the older steel blues differently than newer, so good accurate directions may be hard to find. as I recall you had to bake or heat them in the oven for a time to set/cure the finish or accept the coloring. it was over 30 years ago so I'm sure things have changed a bit.
my train of thought was to use the smaller internal parts as first in process and adjust/redo as needed then do main frame and cylinder..
you could do a test area somewhere on the frame covered by the grip. don't do any internal working parts as it actualy changes tolerances. I know, how much could it possibly change them? for me a nickel plating of a sig frame ended up costing me 300$ to replace the whole frame when all I needed was a pin. off by a rch can make a big diff.
haha.. whats funny is if it did change tolerances it would only help!! the thing is sooooooooooo sloppy its not even funny..
Bluing is actually just he metal itself reacting with a chemicals at higher temp. It differs from plating alot and will not add material to the existing metal.. its more along the lines of a really tough wax job then compared to plating.
that was my chemistry based job.. plating company that did powder coating, epoxy, zincs, moly and ceramic coatings. I was lab tech and wastewater treatment operator, but got bored horribly and became a professional motorcycle tech instead..
my godfather worked at a "wastewater facility plant", he called it a pickle factory and said it taught him not to bite his fingernails.
