Smokeless powder is coated, often with graphite, so that it will flow through powder measures without hangup. So unless the gun itself has external rust, there is little reason to think that this is internal rust. A bronze brush back and forth twice followed by a dry patch will reveal if it is rust or lead. If lead, then as you say! If rust or lead, then some Big 45 Rust remover wrapped around a bronze brush will do the trick.There really isn't a propellent which would cause "rust" in the barrel. My best guess is it's lead. Scrub the hell off of it with a brass brush and a little gun oil. If that doesn't work who cares? Shoot a couple jacketed bullets out of it and that clean up the inerds.
RHMC24 does kroil neutralize rust? Some one had mentioned something on another thread about a chemical that neutralizes rust. I forgot what it was but if anyone recalls what it was I would love to know so I can write it down. Thanks for the help in advance.After trying other methods & still not satisfied put kroil on a bore brush & swab it back & forth, let stand couple hours wet with kroil. Push a dry patch thru. If it is rust, it can take 4 maybe 6 cycles before the patches come out clean ------>
Rust in a stainless barrel would make me very, very suspicious. The reason why I asked about the finish is that I have a Diamondback that I use for grip fitting, it's a burn victim so I have sprayed it with grey primer to keep the rust from rubbing off. That stuff in OP's barrel kinda looks like burn scale, that's why I'm wondering what the finish is.
Swing the cylinder out and look in the push rod recess in the underlug. If you see a small "S" stamped in there, you have a stainless gun. This stamp can also appear in other places, like under the extractor star. Also, can you take some pictures in better light? Stainless should look like bare metal, but yours look grey.Dunno, 1019#E S/N. I wouldn't know what to look for in that regard.
Looks like stainless didn't come until the 80's, so it may be a refinish.