While those temps MAY cause those colors to appear it is far from hard and fast. The color that can appear in a piece of polished steel when heating depends on the alloy, the atmosphere and any possible contaminates in it (oil, carbon etc) as much as the temperature. Plus the color is extremely thin. I have colors show up all the time tempering knife blades. If I take 1095 and don't do anything about the atmosphere it will USUALLY turn straw at 400f if I put it in a air tight foil packet with a bit of paper the paper will smolder, use up the oxygen and it will probably be blueish. Coloring steel is an art more than a science.

In IMHO Johan Gustafsson is the king. Look at an example of his work.
BladeGallery: Fine handmade custom knives, art knives, swords, daggers

On MIM and spinster metal remember once the binder is gone it is ac completely different animal. Thompson Center has been making spinster frames forever. How many or those fail even firing some crazy rounds for handguns?