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Originally Posted by masraum
Why isn't the case blued? I guess it's a different material than the cylinder and barrel so bluing is not needed?
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It is indeed a different material. In modern times, the steels used for the barrel and cylinder are high carbon, what we call "through hardening" steels. As a result of their high carbon content, when we heat treat them they assume a consistent hardness all the way through. This is desirable as it adds considerable strength to these components, allowing the use of high pressure smokeless powder loads.
The material used on the frame is a very low or zero carbon steel. The frame does not need to be nearly as strong as the cylinder and barrel. These steels will not through harden, or actually will not harden at all, when heat treated. It's the reaction that the carbon undergoes that serves to harden the steel.
To harden these low or no carbon steels, some form of carbon needs to be introduced when we heat treat them. Even then, since the carbon is not in the steel, nor can it penetrate the steel, there is no way to through harden these steels. We can, however, surface harden them to help toughen them up against normal wear, scratching, and whatnot. This is referred to as "surface hardening" or, in old time parlance, "case hardening". Hard on the outside, soft and malleable on the inside.
The finish seen on this Colt is known as "color case hardening". It's also known as "bone pack hardening", owing to the method used to introduce carbon in the heat treating process. We pack these things in bone meal - ground up chicken bones with some charcoal and throw them in the heat treat oven. The coloration is a result of the way in which the steel reacts to the bone meal. It's never the same way twice.
In the old days, when these were first designed, the barrels and cylinders were not heat treated, but they were made from the steels then available. The frames, however, were cast iron, a notably weaker material. The cylinders and barrels (and steel grip frames) would accept blueing, the cast iron frames would not. Plus they were soft and prone to surface damage. Bone pack or color case hardening was developed to toughen up these surfaces. This is, by the way, why these guns are not safe with smokeless powder. They just cannot handle the pressures. Colt did not allow for the use of smokeless powder in these guns until the early 1900's.
So, there you have it. The result is a rather pretty gun, IMHO. Here are a couple more. Notice how completely different they look from one another and from the ones in my first post:
Quote:
Originally Posted by Captain Ahab Jr
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In certain neighborhoods I believe that would get you an invite. You might have to think long and hard what sort of person you would bring as your date, though.