I separated out a bunch of Lyman 375167 bullets I cast for my 9.5x57 Mannlicher-Schoenauer caliber and oven heat treated them. The bullets were cast from one pound of monotype to two pounds of pure lead. There is about 6% antimony and 3% tin in them. Should also be small amounts of arsenic. Anyway, they tested out a Bhn 14-15 originally (air dropped onto a towel). They showed about Bhn 20-23 shortly after quenching. I expect they should top out somewhere around Bhn 24-26 (maybe higher) in a week or two, from what I have been reading.

They were sized before heat treating. It should be interesting to see if I can go to higher velocities with heat treated bullets. The originals started losing accuracy fast at about 1,800fps, which was far below the speed where visible leading occured. I ran the heat treated bullets through the lubrisizer afterward and since they had been sized before, there were no problems doing that. I am using Tamarack lube, which seemed to keep the leading away.

HarryO, Keep us posted on this. I can't remember reading a direct comparison with bullets of the same alloy/batch. It should be interesting. Please keep track of the time/hardness curve, and the velocity/accuracy differences between both types. It may just push me into heat treating, as opposed to just water quenching.

This time I am mainly interested in the uniformity of the heat treating and whether or not it has a positive effect on accuracy. I tried dropping some different bullets into a bucket of water a couple of years ago, but the uniformity was poor. The accuracy was also poor and I think the two things were related.

Air dropping seems to be relatively more uniform, but because they are so much softer, the same percentage difference would be a smaller Bhn number. I intend to check several of the oven heat treated bullets after they have had enough time to stabilize and see what hardness they come out at. Hopefully, they will be more uniform.

I tried to get some readings on the heat treated bullets tonight. No luck with my homemade comparison tester. I place two lead pieces (one known hardness and one unknown) in it with a ball bearing inbetween them. Then a nut & bolt squeezes them together. The ratio of the square of the indentation diameters tells me how hard one is in comparison to the other. I have a machinists scale and a 10x magnifier to measure the diameters.

At first I tried from my strip of purchased soft-pure lead (known hardness). There was no mark on the hardened bullet -- and a huge indentation in the soft lead. Too far apart to get a good reading.

So I put the unhardened bullet on one side and the hardened bullet on the other side. I had previously measured the unhardened bullet against the soft lead and determined it was about Bhn 14-15. This time, the marks were there, but they were not big enough or round enough on the hardened one to get an accurate Bhn.

As near as I can tell, the hardened bullet is probably at least twice as hard as the unhardened one. Maybe more. That explains why I could not get anything with the soft lead. The difference in hardness was probably a factor of 6 or more apart. I have to think about getting an LBT tester or something that can take a reading from harder lead than mine does.

I intend to load some up and see how much velocity I can get before the accuracy goes to hell. Will have to wait for a break in the weather for that though.