I really like the way you think. NICE job...
I'm not surprised that blasted metal holds the coat better.
What type of media did you use? Hard or soft? Just curious.
My favorite finish that I use on my own firearms is using a softer media (think baking soda) and then blue it. It comes out almost looking like I parkerized it. Very durable and a flat color. Two things I like.
Your approach has all that. THANKS.