Naphtali,
N: It is delightful to correspond with you. Your clarity is refreshing and reassuring.
F: Thanks!
N: Having the knowledge that bullet is loaded from the muzzle, does your reference to alloying no more than one part tin to 30 parts lead remain accurate?
F: Yes, 30:1 should be all the tin you'll ever need for this kind of use. More is not only unnecessary but wasteful; tossing good tin (money) down range.
N: If I wanted to experiment with tin:lead ratio, how do I establish a baseline casting metal, then return to it before changing one variable? I have a Lee Production Pot.
F: Make up small test batches of the alloys you wish to test one by one, keeping track of the test run of bullets (probably 20 to 40 bullets) made with them. Drain off the unused alloy each time, retaining it for use later on when you determine which fits your need best.
N: Apparently, dropping cast bullets from the mold into a pail of water — that is, water quenching — causes them to be significantly harder than bullets dropped to a soft damp towel — that is, air quenching. If this is true:
F: Quenching bullets, that is heat-treating them for additional hardness can only be done if they contain antimony.
There are various way to do this heat treatment. Some drop bullets from the mold into water as you say. Others heat them in an oven to a specified temperature and quench them all at once. I've done it but it is not worth the additional effort to me these days. I cast to the dry towel and load them as-cast soft.
N: Stored one year at room temperature, does BHN of quench-hardened bullets change significantly? If yes, how?
F: Yes, but again only when they contain antimony. I'm no metallurgist but I believe it has to do with the cyrstal structure of the alloy meshing/fitting tighter together as the alloy ages.
I also know that lead/tin alloys or plain lead is not stable at room temperature. As compared to steel you may think of lead/tin alloy at 70 degrees as being at a the same temperature as steel is at dull red heat: It is still plenty hot enough for cemical reactions to take place. This is one primary reason I like antimony in my bullets: They are stable at room temperature and do not change shape as do lead/tin will over time. It is also why as-cast soft bullets "age harden" over time.
N: If BHN of quench-hardened bullets changes, how do I stabilize at the higher BHN for storage more than one year?
F: Once heat treated the bullets take about 24 hours to come up to full or maximum hardness. After that they remain quite hard for long periods of time, only becoming very slightly softer after several months pass, then stabilizing (still quite hard) after a couple years.
Good afternoon,
Forrest
