Does lead harden over time?

[carbine]

Cleaning the basement and found two 100 lb. stashes of Minie balls. They were dead soft 20+ years ago. They now measure Brinell 8 similar to 40:1 Lead Tin. If I remelt them will I get a different hardness? TIA

[mr surveyor]

is that hardness homogenous throughout the bullet, or is it strictly related to the outer "skin"?

just asking


jd

[GARD72977]

Yes lead hardens over time. If you re cast them they will start off soft and harden over time again.

When you say they were dead soft what dis they measure. Usually they will harden a point or 2. Over time depending alloy

[carbine]

They were a 5 and now an 8. Will remelt and see what I get. Just finished casting up 280 pounds for next year.

[David2011]

I know that alloys age harden but am not aware that pure age hardens. Did you test the hardness when they were new or just assuming that they would have tested softer when new? Don’t take offense; just trying to apply a low level of scientific process. Is there any corrosion present that could contribute to surface hardness?

[GregLaROCHE]

I have experienced lead hardening in a years time. Seems like the boolits got harder than the ingots. I’ve seen it posted, that after they get hard, hardness can go back down some. I can’t confirm if that is fact. Maybe someone else can.

I think if you remelt then they should return to what they were before.

[osteodoc08]

They also grow a touch too.

[Dusty Bannister]

Pure lead does not age harden. You may be working with scrap with a minor antimony content, but pure will not age harden because if it did, it would not be shown as having a BHN of 5 or less.

I have a sample of pure lead from Bill Ferguson that I use to verify my Cabin Tree hardness tester and pure lead is less than 5 BHN. That sample is at least 10 years old by now so if it was going to age harden, is should read more. Dusty

[OS OK]

This ^^^ & this... http://www.lasc.us/Kelter_Cast_Bullet_Alloys2.pdf

[8mmFan]

So...If I cast a bullet, load it in a cartridge, and then put it away for 20 years, I can expect the point of impact of said cartridge to change over time? I'm assuming that different bullet hardness would affect accuracy...

8mmFan

[David2011]

Lead alloys change in hardness over time. Pure lead will not. I was trying to tread lightly in my previous post. I try to size boolits asap after casting them because a two week delay can make them much more difficult to size. Age hardening starts very quickly with some alloys.

[GregLaROCHE]

So...If I cast a bullet, load it in a cartridge, and then put it away for 20 years, I can expect the point of impact of said cartridge to change over time? I'm assuming that different bullet hardness would affect accuracy...

8mmFan

To a point yes. How much may not even be detectable.

[Dusty Bannister]

The original post was regarding what was supposedly pure lead, not a cast bullet alloy. Do not get too confused about the details and get lost in the weeds. Go back to the books. Antimony in a lead alloy will result in age hardening of the alloy. The amount of antimony determines how rapidly this occurs. Most commonly used alloys for bullet casters will be nearly at their maximum air cooled hardness after about three weeks. Lyman Cast Bullet Handbook, 3rd edition gives some idea how rapidly this occurs in cast bullets. Copies are still available if that information is desired. Dusty

[GARD72977]

From what the OP posted it is not 100% lead. It is very easy for people to think they have pure lead and it turns out to be different.

[Dieselhorses]

Glad this was brought up-it reminded me that whatever I'm casting, to cast with alloy a few points lower since it takes a while for me to get away to the range sometimes. Some of my stored bullets have gotten way up there. Only deal with 3 alloys COOW, tin and pure lead so I really need to start paying attention to my mix.

[OS OK]

Glad this was brought up-it reminded me that whatever I'm casting, to cast with alloy a few points lower since it takes a while for me to get away to the range sometimes. Some of my stored bullets have gotten way up there. Only deal with 3 alloys COOW, tin and pure lead so I really need to start paying attention to my mix.

I thought that I was using pure Pb (roof flashing) and adding Sn to target a 8 BHN blend for .45ACP HP's. In reality and only a week later it was 9.2 BHN, still is 10 months later.

I think you have the right idea.

[GregLaROCHE]

Mixing metals can really be mysterious.

[curator]

Carbine,

Your Minie' ball alloy was probably 1 to 2% Antimony (Sb). That alloy will age harden to about BHN 8 over several weeks. That is a common "range scrap" that is mostly .22 rim fire bullets. If you want to use them and also want them to be as soft as recent castings, simply heat them to 450 degrees for an hour or so and let them cool slowly. They will remain nearly dead soft for about 2 or 3 days. Shooting round balls cast for my C&B revolvers that were made from clip-on-wheel weights (probably 3% Sb), I "cook" them the night before. After cooling overnight they test a hair over BHN 5. They load the same as "pure" lead the next day. After two weeks they test BHN 12 again.