My shotgun had blood on the barrels . And it's removed the bluing. Was before I bought it . Took the shotgun to a shop when I thought about trading it in and the RFD said it was blood from pheasant 's. He knew my boss who I had bought it from and he had sold the gun when new to my boss.

Yep , it removes bluing https://www.dropbox.com/s/2nwdryoca0...41732.jpg?dl=0