As to blood destroying bluing...I have no clue...
But a few years back, I wanted to 'age' a new barrel that I had fabricated and screwed into my C96 Mauser barrel extension...I asked here what was a way to make steel acquire the 'patina' of 90 years...George Anderson replied that I should soak the part in urine...
I wasn't sure if old George was messing with my mind...but it took a couple days to fill a liter Coke bottle anyway...So I tried it...
And to my utter amazement, it turned the bare steel a dark black-ish color...It now sits on my infamous 'Red Five' C96, and most people have no idea it isn't a result of natural oxidation...
I've heard that this is also the treatment that Japanese swordmakers use to heat-treat steel blades...
Now, I don't know if urine has the same effect as blood on bluing, but I would no longer be surprised if it did...
(Before & after, finished barrel [bottom two] straight from the Coke bottle...)
