ED;
As I pointed out original heat treating of the receiver in a case hardened part will begin to be affected as temps exceed about 350F. You can verify this from any edition of Machinery's Handbook or virtually any book or treatise on heat treating &/or metallurgy. I would define low temp as any temperature not exceeding this, not really a difficult definition.
My responce was to "Your" statement that it was low temp because it did not exceed the critical tmperature of the steel. "IF" that is your definition of low temp then you do not understand the term in relation to heat treated parts, Period.
As best as I can determine from looking at a picture the parts in question have the appearence to me of being temper colored. I have in the past chemically colored the receivers of a few inexpensive gun frames using the method which heated the part to around 160-165F & the chemical was then daubed & streaked on with a Q-tip. This does not raise the temp high enough to have any affect on the heat treat. These parts do not have the same appearence. Temper colors on the other hand cannot be obtained with out the temp being high enough to affect the hardness of the part. Once more the critical temp "DOES NOT" have to be reached for this affect to take place.
So one more time "YOU" are the one who said the heat treat was not affected because the critical temp had not been reached.
It would pay you Sir to learn the definition of "LOW TEMP" in relation to heat treating & tempering or drawing hardness is concerned. "IF" you can't define it how do you know you haven't exceeded it.
