Heat Treating

HEAT TREATING:  The following is an attempt to explain the process of heat treating that is required for certain parts. First and foremost, it aint easy if you have never tried it before; but its not so hard that any individual with his mind made up to learn couldn’t get the hang of it. I do suggest you experiment with some “spare parts” before you actually start on the real thing. One way you will know whether you have successfully hardened a part is if your file won’t cut it. Alas! You did it!

Basically, the process of heat treating involves two operations. First to harden, which involves heating the part to the right stage and then quenching in the right medium; second, to temper or “bring down” the hardness to the proper hardness.

Getting Ready for Hardening. For most of us who don’t have a full blown machine shop to spoil us (guess that doesn’t include me anymore), you will have to find a source of equipment to provide an open flame hot enough for the first step. Use an acetylene torch preferably, forge if lucky, or propane torch (pitifully inadequate), or MAPP gas (hotter than propane and readily available but will require using two to get enough heat on large parts). You will need some wire to hold the parts (which won’t draw out heat) and some light motor oil (the real stuff) in a can or metal bucket. Don’t skimp; you MUST submerge the part in the oil.

Hardening. Attach the wire to each part to provide you with a good control handle. Heat the part uniformly to a bright red (about 1500 degrees). Very quickly immerse part in the oil and twirl around for about 30 seconds. NOTE: When you first immerse the part it WILL flame but will quickly go out. DO NOT withdraw until the part has completely cooled. This is deep hardening. At this time, the part is so hard it is brittle and must be “tempered” to draw some ductileness back into the metal.

Tempering. A frizzens hardness must now be brought down to a RC 62-64 at 375 degrees; a pale yellow color on the parts exterior. Sears, tumbler and fly must be heated to 600 degrees, which is an RC 54-56 and will look full blue with some areas fading into gray over the parts exterior.

Note:  It’s a good idea to have a builders group of screws for the gun you are working on, and then your finish quality screws for the final assembly.  Back file the slots so the slots are not perfectly vertical. They will release your screwdriver easier without fouling the top of the screw head. Then heat treat the screw heads of the lock, tang and wood screws you finish up with. That way, you stand a better chance of not boogerin’ up the slots later! You can either oil harden them by red heat and dip in oil, or red heat and  dip in kasenit for super durability.

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