I made a lot of cast bullets years ago and I know a lot about the metallurgy. Lead pipe should't be alloyed with with tin or antimony. That's a real problem. Tin is expensive to buy. I used wheel weights io get antimony and I could get a few pure tin igotts from work. I had x-ray equipment to analyse for exact composition.
I would look locally for a company that sells lead alloys for casting bearings. There was one near me I told them I wanted something close to linotype. They blended it and cast it into small ingots while I waited. It cost to much to buy 50/50 soldier as a source of tin. A bearingg co. could sell you tin and antomony to blend with your pipe lead. A hardness tester won't relate to the tin content. Animony cntributes most of the hardness. You can judge if you have enough tin by how sharp adges are that should be square like grease groves or the back end. Tin improves the fluidity so the lead fills the mold properly. Grease groves get square edges and not big rounded edges. You must size them to match your rifle bore. You shouldn't try to shoot them as cast. You need to run them thru a sizer to get the gas ckecks attached to the back end.
You can actualy heat treat lead alloys to increase the hardness. t's been about 50 years since I did it. The NRA Cast Bullet Manual is on E-Bay for about $50 covers the process. Basically you put them in an oven about 50F below the melting temp. Maybe try 350F for an hour and I think they were aair cooled. The process has something to do with putting the antimony into solution. I'll try to find a write-up.
Wheel weights are now made from zinc, no longer a lead antimony alloy.
I don't know if it's worth bothering with cast bullets unless you plan I shooting them for many years. Don't know currant prices but I think your looking at $300-$400 or more. Plus the tin and antimony.
Melting pot
ladel
molds
sizing lubricating press
sizing dies
gas checks
bullet lube
Good explanation for heat treating Pb alloys. Doesn't give imes and temp. Will look for more info.
Explore the methods of strengthening lead and lead alloys for various applications, including battery components. Learn about the challenges and successes in solid-solution hardening, solution treating and aging, and dispersion hardening of lead alloys.
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