Jerry,
When I get a chance, I will start another thread on heat bluing with one of these heat tapes. After talking to you a while back, you told me that a good heat blue on steel took an even heating to about 550 degrees F in air. I started to set up a rig made out of a heavy copper tube wrapped with the heat tape and controlled with an electronic thermostat. The rig would be mounted horizontally on short legs. The cleaned barrel would be held in the center of the tube with brackets on the inside of both end caps. Because of the thermal conductivity of the copper tube wall, the heating is very even throughout the length of the tube. And since the bluing is an oxidation process, I started to set up to bleed oxygen from a welding torch through the tube while the barrel is heating. I am building a matched pair of silver mounted, rosewood stocked pistols with gold inlaid decoration on the barrels. I intend to heat blue the barrels in this manner.