I'd bet the government started doing this to save time and increase production. If you don't have to plug and unplug a bore it would go faster, and in the long run be cheaper. I never thought about the possibility of the plug blowing out. I just have never noticed the inside of a barrel being blued. You learn something every day. My Dad was an old time pharmacist that still did compounding when most has stopped. Several times a year, a local well-known gunsmith would have dad make up a pint of bluing from a recipe that he had. He made it for them for 40 years or more. It had some poisonous chemicals in it and required care in mixing.I don't even know if a person could get the chemicals these days. The gunsmith was known for his great bluing jobs, so it must have been good stuff..
Last edited by reivertom; 01/14/20.
