Spindrift
Well-Known Member
I currently have two alloys in use, one of which is nuclear medicine lead, with 2% tin. I have cast loads of bullets with this alloy, with different kinds of aluminum moulds.
Air cooled hardness (day 1) is around 11, increasing to about 14-15 after a couple of weeks. With water quenching, I have got BHN 15-17. I have tested for hardness a bunch of times, different kinds of bullets in different calibers. Alloy performance has remained predictable.
The other day, I cast my first HP- bullets with this alloy, from a MP brass mold (311-180). This is not only my first HP- mould, but also my first non-aluminium mould. During the same casting session, I also cast some lee CTL312-160 with exactly the same alloy, when the brass mould needed a little break. All bullets water quenched, except a few «rejects», that were dropped on a towel and air cooled.
Today, I did hardness testing (monitoring alloy consistency).
Air cooled bullets, day 1, BHN 11 (as expected)
Water quenched bullets from 2- cav aluminum Lee mould: BHN 15,4 (as expected)
Water quenched bullets from brass MP- mould: BHN 20,9 (What??).
It must, obviously, be about heat. Nothing mysterious. But quite a surprising effect, anyway.
Air cooled hardness (day 1) is around 11, increasing to about 14-15 after a couple of weeks. With water quenching, I have got BHN 15-17. I have tested for hardness a bunch of times, different kinds of bullets in different calibers. Alloy performance has remained predictable.
The other day, I cast my first HP- bullets with this alloy, from a MP brass mold (311-180). This is not only my first HP- mould, but also my first non-aluminium mould. During the same casting session, I also cast some lee CTL312-160 with exactly the same alloy, when the brass mould needed a little break. All bullets water quenched, except a few «rejects», that were dropped on a towel and air cooled.
Today, I did hardness testing (monitoring alloy consistency).
Air cooled bullets, day 1, BHN 11 (as expected)
Water quenched bullets from 2- cav aluminum Lee mould: BHN 15,4 (as expected)
Water quenched bullets from brass MP- mould: BHN 20,9 (What??).
It must, obviously, be about heat. Nothing mysterious. But quite a surprising effect, anyway.