Ron,

Looks like you are on the way to a wonderfull blue.

Yesterday I was thinking about rust blueing. I've forged and polished many Japanese style swords which have given me an education in steel surface peculiarities. In polishing the swords, I would use mold polishing stones to 800 grit, then sandpaper to 2000 grit, and finaly use the "jizuya" and "hazuya" traditional finger stones. After useing the finger stones, the blades would rust VERY quickly. Sandpaper has a burnishing effect which smears the surface of the steel and closes the grain. The stones break down quckly and have little or no burnishing which leaves the steel grain open and reveals the hamon (temper line) and other characteristics in the steel from the heat treating and forging. Open grain rusts fast.

With barrel steel typicly being 4140 which has a touch of chrome, I can't help but think the open grain condition would help in rust bluing. Maybe use sandpaper to 320 then use a soft 320 or 400 grit stone useing windex as a lubricant. Degrease as you polish, plus the stones leave a nice, crisp finish at the edges. I am going to give it a try and let you know how it works if you like.