Right the bore is left in the white. what I do is use a wood dowel of approximately the bore size (.50 cal. 1/2 inch dowel). Plug the barrel with the dowel positon upright so the bore is pointed down (I use my bench vise on the dowel not the barrel) and then blue, never tried to brown, but my cold blue jobs usually end up brown over time :hmm:
Waya :m2c: