Take a rifle cartridge, 30-06 will do, flatten the mouth and use the flat edge on heavy deep rust.
Done that with light oil on rust that 0000 steel wool is to deep to reach for years, doesn't hurt the blue.
I do like the copper pipe idea, will have to try that.
Done that with light oil on rust that 0000 steel wool is to deep to reach for years, doesn't hurt the blue.
I do like the copper pipe idea, will have to try that.