Ed,
I case harden as a hobby and do only work for myself. There are those who do it professional and know much more than I. I have case hardened over15 actions. Fortunately I have never had any problems with warpage or cracking. From my research I have learned that quenching at too high a temperature or not properly anealing the action can lead to warpage. I did have a Parker action hardened by classic guns that required the barrels to be refitted. I admit that rehardening is not without risk. I will post photos of my work as soon as I can get help from my brother posting photos.
What temperature does your gunsmith use? What chemicals does he use? I have know people who could get colors using heat and cold blue? I have never tried this. I believe that your gunsmith is using a torch because of the color and pattern of the color. The bullseye look is only obtained by using a torch. These type of colors are temper colors and occur between 450-600F. If he used a kiln it would heat the parts evenly and there would not be much variation in color. The different colors developed due to differences in temperature. Purple at around 530F, blues at 560F, etc. Your gunsmith may use a kiln to pre-heat the parts to about 400F and the get the different colors by locally increasing the temperature in different area of the action to produce temper colors.
Ed I'm not trying to pick a fight with you. I don't care what you have done to the guns you sell as long as you accurately describe them. I don't even believe that this process has caused any serious damage other than softening the action. That is if he did the coloring with the action completely disassembled.
