I suggest you de-grease everything using MEK or Acetone. Just work outside and away from any flame source. When we were bluing a lot of handguns, we used wipedowns using MEK and that eliminated the need for cleaning parts in boiling silicate detergent. And we never had any parts which needed to be re-blued. Same should be true with rust bluing. I would not recommend barrel removal - it is not necessary.