[Hugh]

John, I mean the reciever (bbl extension), the "handle part" is the frame. Carbon steel is annealed (removing hardness) at around 1000-1400 deg, depending on the amount of Carbon in the steel. This temperature is usually attained at a dark red or "cherry red" color. It is hardened by heating to 1500-2000 and "quenching", or cooling rapidly by dipping into some type of oil or brine water, depending on the type of steel. After hardening it is very brittle, and must be "drawn" to remove the brittleness. This is usually done by bringing the piece up to a lower temp slowly and letting air cool slowly. The drawing temp can be anywhere from 300 to 800 degerees. If you are making a spring for instance, the drawing temp is around 800 deg. For other parts such as Luger small parts, it is a lower temp (which gives the "strawed parts" their distinctive color). The "fire blue" color is attained at a temp of around 550-600 deg. For a part that has already been tempered and drawn, reheating to this temperature will not effect the hardness or toughness of the metal because this was probably close to the "drawing" temperature anyway.