Is there a rule of thumb as to the finish of a barrel and lock? I have a barrel that will not keep bluing. Any thoughts?
What process are you using?
I have tried commercial rust blue from Brownell's that where I live quit working in 3 coats. Grey-blue at best.
I have found that Wahkon Bay brown and Wahkon Bay AF stain mixed maybe 50-50 does a great job as a rust blue agent. No matter the alloy 4140/50, 1137 or whatever.
Your really need some nitric in the mix to get better blue in my experience.
Dan