Forget about trying a express blue for finishing composite barrels. I have done lots of experimening and it doesn't work. They always come out blotchy and inconsistent.

Tradional rust bluing is the only(jmho)method to finishing composite barrels.

Tom Flanigan's method is very accurate. Only a few points i wouldn't agree with, but who knows i could be wrong too.

Also i wouldn't waist my time with logwood powder. Get the chips/shaving from Aurora Silk.