Wonder why if high temps for brief periods of time are inconsequential or ineffective, why then historic caution to keep the brass below the shoulder from ever going above 450 F?
Curious also that since brass is an alloy made of roughly Copper (70%) and Zinc (30%), are the effects of raising a brass case's temperature above Zinc's melt temp of 420°C (787°F) the reason for the traditional 750 F max neck temperature?
Interestingly the outer core of a candle's flame (light blue) is roughly1400 °C, and the inner red portion is around 1070 K (800 °C). Both are more than hot enough to anneal according to a old school method of using a candle to anneal. It's done while holding the case in your fingers above the head while rotating it until it is to hot to hold and dropping it on a wet towel and wiping the carbon black off. Slow and unscientific yet anecdotal evidence says it works, and gives consistent results which is my purpose for annealing. Brass life is a bonus.
I don't use a candle, I use a Gen 2 Burstfire with a grill propane tank and a regulator. It check it with a laser temperature gun and Tempilaq 750.
From AMP's web site:
- Cartridge brass melts at 915°C (1679°F). Up to that temperature it remains homogeneous (Appendix 1 - 1.1).
- Dezincification of brass can occur because of chemical attack, but heating brass, even to high annealing temperatures cannot cause dezincification unless chemicals are present. The zinc content of the alloy cannot burn or melt out up until boiling point (Appendix 1 - 1.6)."
I cannot opine as to the "historic caution" of never going above 450F or the erroneously propagated "750F max neck temp" to anneal brass. If I had to guess, someone saw a chart indicating brass would anneal at 750F but failed to also see that it required 1 hour at that temperature.
I know when I started in my own profession in the mid 1990's, there were many things done, especially in the OR, because "it has always been done that way" or "it just made sense". In the last 15 years we have moved away from this methodology and now practice "evidence based medicine". With proper scientific studies it was discovered that many of the "traditional" things we did provided no benefit to the outcomes, and in some cases were detrimental. This, and for many other reasons, is how I know Dr. Fauci is a QUACK. He went on national television and said "It just makes sense that two masks are better than one." We don't practice this kind of medicine anymore. Where is the double blind, placebo controlled study to show that two masks are better than one?
I think long range shooting has entered a similar period, where we are applying science to see what actually affects the outcome versus what "traditional methods" have no effect or are, in fact, detrimental.