Gun Metal Blueing Copper

[plbetsch]

I need to turn 50 12" long copper tubes black, or a color simular to gun blueing. Currently I've been testing a process where I polish the tube, then clean with methylene chloride, clean with muriatic acid, then wipe on gun blueing (selenium dioxide). This works but I'm wondering if there is a better method or if Caswell offers a product that I can just wipe on that would be better that the gun blueing I'm using.
I currently just want to do 50 tubes cheaply so I don't want to buy a plating kit but if this sells then I would need to do about 5000 tubes and be looking for a kit or complete finishing system. Any ideas?

[boogie68ss]

being a gunsmith myself... sounds like a black krome kit is exactly what you want. i use one for various jobs. never applied it directly to copper but the manual implies it will plate to copper.