454PB
04-25-2013, 10:19 PM
There's been considerable discussion about the differences between old and new wheel weight alloy.
None of mine are what I would call "old", the newest ones I have were acquired about 5 years ago, and there's really no way to determine when they were made. I do know that I haven't yet found any Zinc in them, if that says anything.
However, today I dug out some boolits that I cast in January of 1983. I always insert a note with each batch of boolits noting the alloy and cast date. Obviously, if they were cast 30 years ago, the wheel weights are older than that. Some of these where air cooled, and some were water dropped.
I did hardness tests on two samples of each, using a Lee hardness tester, testing on the boolit nose. The mould used was a Lyman 452424.
The air cooled samples came out at just over 14 BHN, the "quenched" ones were 17 BHN. I haven't a clue what hardness they were 30 years ago, because I didn't have a tester back then.
From tests done since I have had a tester, I've found that quenched wheel weights of more recent manufacture (at least they were acquired most recently) take about 2 weeks to reach 25 BHN. I tested some RCBS 270 SAA that were cast and quenched 4/05/13 using wheel weight alloy plus 3% tin and they are at 28 BHN. I've also seen from previous testing that after about 18 months, they begin to re-soften very slowly.
If I can assume that the 30 year old quenched boolits were initially as hard as the most recent ones, they lost 11 BHN hardness in 30 years......but that's a lot of "assuming".
None of mine are what I would call "old", the newest ones I have were acquired about 5 years ago, and there's really no way to determine when they were made. I do know that I haven't yet found any Zinc in them, if that says anything.
However, today I dug out some boolits that I cast in January of 1983. I always insert a note with each batch of boolits noting the alloy and cast date. Obviously, if they were cast 30 years ago, the wheel weights are older than that. Some of these where air cooled, and some were water dropped.
I did hardness tests on two samples of each, using a Lee hardness tester, testing on the boolit nose. The mould used was a Lyman 452424.
The air cooled samples came out at just over 14 BHN, the "quenched" ones were 17 BHN. I haven't a clue what hardness they were 30 years ago, because I didn't have a tester back then.
From tests done since I have had a tester, I've found that quenched wheel weights of more recent manufacture (at least they were acquired most recently) take about 2 weeks to reach 25 BHN. I tested some RCBS 270 SAA that were cast and quenched 4/05/13 using wheel weight alloy plus 3% tin and they are at 28 BHN. I've also seen from previous testing that after about 18 months, they begin to re-soften very slowly.
If I can assume that the 30 year old quenched boolits were initially as hard as the most recent ones, they lost 11 BHN hardness in 30 years......but that's a lot of "assuming".