Maybe Dakota use a steel that can be CCH. Like JE has said, proprietary information. When Colt brought back their SA Revolver, they had to run an extensive R&D program to CCH the frames like the original were. All of the men who had done the CCH on the originals were either retired or passed on. How many thousands of $$$ were spent? Only Colt knows. I know I spent a lot after taking the basic, week long NRA Summer Gunsmithing class, at Murry State in Tishomingo, to get the basics of CCH. It was just a place to start. A good heat treat oven, obtaining suitable media (different types of charcoal), building crucibles and the tools to handle them when they are "cherry red hot", building a quench tank, and then many, many hours of 'experimentation' to learn what worked and what didn't. That was for the original, charcoal packed CCH process. Evidently, there are some other processes that mimic case colors. Doug Turnbull has a bunch of that figured out, as he's one of the only I know of that can/will color 4140HT, 4140HT being the alloy steel used by many manufactures for their rifle receivers. But I don't think he will do a centerfire rifle receiver, from what I have been told. There are many other alloy steels that are lower in carbon content that CCH very nicely, like 8620 that I mentioned previously. 8620 being chrome .50%, nickel .55%, molybdenum .20% with a carbon content of .20% +-. Most steels in that .20% content seem to color nicely, and quenched at the proper temp produce a good, hard 'case' on the outside. Provided with the proper 'controls', temp of the part before quench, time held at that temp, the carbon bearing media that the part is 'packed' in, the temp of the quench, the steel itself, repeatable case hardness and colors can be reproduced from part to part. Then their is the warpage to contend with when going from high temps required for most heat treating processes (CCH included!) into the quench. Not done properly, the 'part' being CCH may warp enough that any additional 'parts', needed to complete the final assembly, may no longer 'fit'. It's just not as simple as it all appears to be. The placement and 'coverage' of a 'part' with case colors is completely at random, no 2 are alike.