There has been more written on this subject than the average person reading life span could comfortably take in but none the less here goes. Firstly if you want a high gloss finish the rust bluing solution used should be along the lines of “Swiss Black” (beutel) or failing that a low level Acid formulation especially low on the Hydrochloric acid, this has a tendency to etch the metal surface and in doing so reduce the high surface gloss you are looking for. If you really want to produce a high gloss blue the final grit size should be around 800. Though my personal opinion of extremely high gloss barrels is like taking a double set of mirrors with you, so not good news for Pigeon shooting over here because they see the light reflected off the barrels at a distance.
