If you just want a small quantity of blueing salts rather than the big lots sold by Brownells, check out the horological and clock making sites. These guys use the salts for bluing clock hands; I've seen some very handsome results.

I found that placing the polished, clean dry parts onto a brass plate and playing a gas torch underneath was easiest. When you get the right colour, I just flicked the part into a beaker of cold water, and followed up with de-watering oil.

Eug

Thank you, very kind. Mine's a pint