I have blued many gun parts with Brownells hot bluing salts in a 50 cal ammo
can on top of a old kitchen stove, It is messy and hazardous, but does a fine
job. I do not think I'd try to use a fryer because the temp is critical and 290
degree caustic eats aluminum bigtime, and stainless gives off color spots on
the parts is used with hot caustic salts