Look into the Brownell's modified rust blue process called "Dicropan IM" It's a solution that's applied after doing a polishing and degreasing procedure and immersing the treated parts in boiling water for 5 minutes. A heavy surface rust forms, which is carded off with degreased 4-0 steel wool. It takes at least 5 or 6 applications, but the resulting blue is deep and durable. A Swedish Mauser that I blued that way in 1986 still has the blue in good condition, and I haven't pampered it.
Jerry
