BHN decline over time - estimated curve?

[huntinlever]

Things are really in flux and I want to cast all my alloy before the next few months are up. That would be something over 1000 bullets, on top of several hundred I currently have on hand. 2:1 Pb: No. 2, WQ'ed. Estimating around 18 BHN, no idea of that's a decent guess. Any way of estimating how the boolits will soften over time?

FWIW, shooting gc'ed 45-70 at about 1575 fps, 0.460", with a bore slugged at 0.458."

[hermans]

Hmm....I have never had them softening over time, only hardening up to about 3 months after casting, thereafter they stay more or less at the same BHN.

[Hick]

The book Ingot to Target has a table on age hardening and softening of different alloys
Lead/antimony/tin

Pure lead does not change

97/2/1 starts out at about 9 bhn but ultimately gets to about 18 in 6 months
94/3/3 starts about 12 ends up about 17
82/12/6 starts about 20 but softens to about 18

I am simplifying a lot- for details you need to look at the book.

[megasupermagnum]

I'm only aware of one person doing a 1+ year test, and that was TATVcanada on Youtube. You can find his videos easily. Basically there is very little change at 1 year, they are about leveled off at that point. I'm not aware of anyone doing a 5+ year test, but that's likely the timeframe you would need to see any kind of change.

Short answer, no there is no way of estimating the softening since it has never been tested, or at least tested and shared.

[OS OK]

If I were you, I would start my own 'time/hardness test' with this batch you intend to cast now. Then, this time next year you will know for sure.


https://youtu.be/0wANnVvVMuk

[Willie T]

I am interested in following where this thread goes. Hardest I cast is No2. Gas checked it is hard enough for all my purposes. Never noticed it get any softer over time. I will be following what others have found closely.
Willie

[Dom]

I have a considerable amount of scrap WW's I have collected from 30 to 40 years ago. They still tests at 10.5 BHN. As yet I have never seen a change.

[megasupermagnum]

I have a considerable amount of scrap WW's I have collected from 30 to 40 years ago. They still tests at 10.5 BHN. As yet I have never seen a change.

That's aircooled though, it can't really soften more than that. The OP is asking about quenched bullets. There seems to be a certain thinking that quenched bullets are only hard for a certain amount of time before they are the same as air cooled, and that's not something I've ever seen a shred of evidence for because it likely isn't true.

[BJung]

My range scrap bullets soften over time. How your bullet reacts depends on the alloy and I don't know exactly what I have. I would cast bullets, let them season for a month, and retest an outlier or two for hardness.

[Land Owner]

BHN too hard? Remelt & remold.
Too soft? Remelt & remold.

1,000 boolits is as "nothing" when the lead and mold are hot.

The act of sizing can significantly work-SOFTEN boolits below their as-cooled BHN. Time and alloy composition change BHN.

Do we believe, for 1 minute, that we KNOW our BHN? We lay persons, without sophisticated equipment and using a box of drafting pecncils, are in the estimation game of BHN. Up or down, BHN is a target and one that MOVES.

[charlie b]

Go read up on the LASC site. A couple of articles in there about age hardening and such, including time tables and alloys.

Yes, it happens. How it affects the bullet depends on where you start. Air cooled, quenched, how much antimony is in the mix, etc.

Sent from my SM-P613 using Tapatalk

[ioon44]

When I stopped commercial casting in 2003, I had some water quenched bullets of 6-2-92 alloy that ran 18 to 20 BHN.

Around the year 2014 I tested some of these bullets and they came out at 15 BHN the same as air cooled 6-2-92 alloy, I don't know at what point they softened, but they did.
These were tested with the same LBT BHN tester.

[huntinlever]

OK thanks guys. I'd thought of getting a lee tester but at the end of the day I'm merely interested in hunting so can accept some variances, just wanted to know if I should expect enough of a difference to affect any ballistics or accuracy. I'll be shooting a lot right up to season anyway.

If anything, I've often wondered if I might be casting too hard anyway. This approximate stable BHN has always done well for me, though for me with the cast 45-70 it's always about punching a clean tube through the game, never expansion. That said I wouldn't mind if these drop a bit.