https://www.totalmateria.com/page.as...site=ktn&NM=88
Some good info . Heat Treating of Lead and Lead Alloys.
Another-
https://patents.google.com/patent/US5464487A/en
EXAMPLE
38 caliber swaged wrought bullets manufactured by Bull-X, Inc. were heat treated in an open air furnace at about 450° F. for the times set forth below and were then promptly quenched in water at ambient temperature. Following quenching, the Brinell hardnesses of at least 25 of the bullet samples were tested with a Rockwell machine in accordance with ASTM Standard E10-84 using a 100 kg load and an M scale ball of 6.35 mm diameter. The duration of the heating and the Brinell hardness readings were as follows:
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Heating Time Brinell Hardness (min.) (range)
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5 minutes19.6-21.3
10 25.5-28
20 24.3-25.5
30 28-29
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After 8 days, 1 1/2 months and 2 months, hardness tests were again performed on these samples and these tests revealed that the hardness was essentially unchanged.
At least 25 of the samples which were heated for 5 and/or 10 minutes and then quenched as described above also were sectioned, ground, polished and hardness tested both at the surface and the core. These tests revealed that the hardness was essentially uniform throughout.
The samples which had been hardened as described were also analyzed for metal content and had the following metal content:
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metal wt. %
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Copper 0.038
Arsenic 0.16
Antimony
3.0
Tin 0.25
Zinc 0.0001
Cadmium 0.0001
Nickel <.0001
Bismuth 0.018
Silver 0.0038
Tellurium
0.0015
Sulfur 0.0005
Iron <.0001
Lead Balance
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It can be seen from the above example that the hardened swaged wrought bullets of the present invention are capable of use in their unjacketed form with ammunition loads of substantially higher muzzle velocities exceeding 900 fps, and in loads having the power factor and bullet weights previously discussed without unacceptable leading. Thus, the cost of jacketing is avoided as well as cost of inclusion of tin or increased levels of antimony.
It will be understood that the preferred embodiment of the present invention which has been described is merely illustrative of the principles of the present invention. Numerous modifications may be made by those skilled in the art without departing from the true spirit and scope of the invention.