Do Cast Boolits Harden with Age?

[wxman12]

Hello All,

I am a novice caster. In fact, cast my first batch of Lee TL356-124-TCs for 9mm about 6-8 weeks ago.
This first batch of range lead, water-dropped boolits tested at 10-11 BHN during the first 2-3 days after casting. Range results during the follwing couple of weeks were dissappointly inconsistent as about 20-25% were keyholing.

After much reading on this and other forms regarding the advisability of shooting slightly oversized bullets to address the issue of keyholing, it finally dawned on me a few weeks ago to test a subset of boolits from this initial batch that measured closer to .357. I took great care to keep all other variables (powder load, OAL, etc.) the same.

Much better results with these slightly larger boolits - no keyholing! So, I'm thinking the mystery is solved, right?

Maybe not. I re- tested this initial batch of boolits today to find them now consistently at 16 BHN! So, now I've got 2 variables (boolit diameter and BHN) where I thought I had only 1 (boolit diameter).

Question: Is it to be expected that cast boolits will harden with age as mine apparantly have? Any rule-of-thumb in this regard?

[Bigslug]

You'll find this link in the Stickies at the top of the Cast Boolits page: http://castboolits.gunloads.com/showthread.php?110213-From-Ingot-to-Target-A-Cast-Bullet-Guide-for-Handgunners

You'll find it invaluable at your present stage in the game. There's also the lead alloy hardness calculator sticky at the top of the Leads & Lead Alloys sub-forum. It won't cover all the heat-treating variables, but it will get you started.

Short version however - most of what we cast with (i.e. wheelweights & range scrap), is going to consist of lead with some antimony as it's primary hardening agent, with a little tin to toughen and help with mold fillout. How the antimony behaves depends on how much is in the mix and how it's cooled. Think of it like steel - a sword that is forged and allowed to cool in open air will have very different properties than one heated red and dunked in water. Water dropped antimonial lead seems to stabilize in hardness after a week or two.

Old school bullets of lead and tin won't water-harden like antimony-based slugs will. These days, they're mostly the arena of the buffalo cartridge gun shooters.

Worth noting - ingots don't cool the same as boolits, and therefore aren't going to hardness test the same. I'm coming up on my next scrap smelt, and my plan is to utilize a SWC mold I don't shoot anymore to cast a few hardness test samples right from the smelting pot. Air cool a couple and water drop a couple before pouring my ingots. This way, I hope to have a very solid idea of what I have before it goes into the casting pot.

[montana_charlie]

This first batch of range lead, water-dropped boolits tested at 10-11 BHN during the first 2-3 days after casting.
What was the hardness of bullets that were not water dropped?

CM

[sqlbullet]

You don't mention what you cast from. WW, isotope, that would be helpful.

My experience is with isotope lead and it tends to age harden to about 14-16 tested with me Lee hardness tester. Water quenched bullets tend to go the other way if initial hardnessnis above 22. The tend to soften down towards 22.

[upnorthwis]

Might want to also try Powder Coating and using a larger expander. Do not size after PC'ing.

[prs]

'Do Cast Boolits Harden with Age?" Yes, unlike men.

prs

[jmort]

Except for the ones that soften.

[Yodogsandman]

My "rule of thumb" for air cooled alloy boolits is to wait 3 weeks and just 5 days for heat treated, to shoot them. This allows the alloy to reach almost all it's total BHN gain. Once stabilized, it will take years to notice any difference of any BHN loss.

[wxman12]

What was the hardness of bullets that were not water dropped?

CM
All were water dropped.

But you're point is well taken - I need to air cool a few from the next run so I can use as a reference.

[wxman12]

You'll find this link in the Stickies at the top of the Cast Boolits page: http://castboolits.gunloads.com/showthread.php?110213-From-Ingot-to-Target-A-Cast-Bullet-Guide-for-Handgunners

You'll find it invaluable at your present stage in the game. There's also the lead alloy hardness calculator sticky at the top of the Leads & Lead Alloys sub-forum. It won't cover all the heat-treating variables, but it will get you started.

Short version however - most of what we cast with (i.e. wheelweights & range scrap), is going to consist of lead with some antimony as it's primary hardening agent, with a little tin to toughen and help with mold fillout. How the antimony behaves depends on how much is in the mix and how it's cooled. Think of it like steel - a sword that is forged and allowed to cool in open air will have very different properties than one heated red and dunked in water. Water dropped antimonial lead seems to stabilize in hardness after a week or two.

Old school bullets of lead and tin won't water-harden like antimony-based slugs will. These days, they're mostly the arena of the buffalo cartridge gun shooters.

Worth noting - ingots don't cool the same as boolits, and therefore aren't going to hardness test the same. I'm coming up on my next scrap smelt, and my plan is to utilize a SWC mold I don't shoot anymore to cast a few hardness test samples right from the smelting pot. Air cool a couple and water drop a couple before pouring my ingots. This way, I hope to have a very solid idea of what I have before it goes into the casting pot.
Thanks, will check out the link.

[wxman12]

You don't mention what you cast from. WW, isotope, that would be helpful.

My experience is with isotope lead and it tends to age harden to about 14-16 tested with me Lee hardness tester. Water quenched bullets tend to go the other way if initial hardnessnis above 22. The tend to soften down towards 22.
Purchased range lead. Don' know much about it otherwise.

I did score my first bucket of wheel weights a few weeks ago. Counter-intuitive, but I will know more about it than I did this first alloy.

[wxman12]

Might want to also try Powder Coating and using a larger expander. Do not size after PC'ing.
Thanks, will make these adjustments.

[wxman12]

'Do Cast Boolits Harden with Age?" Yes, unlike men.

prs
[emoji12]

[wxman12]

Thanks to all for the helpful tips. I hope to implement these over the course of the next few weeks and will let you know the results.

[StratsMan]

I did score my first bucket of wheel weights a few weeks ago.

Be careful !!! Buckets of raw wheel weights from a tire shop will include zinc weights. If you put those in with the lead wheel weights, and the pot gets hot enough, the zinc will melt into the alloy. You don't want that... You need to sort through the wheel weights first, and remove the zinc weights. Some will have "Zn" on them. They sound different than lead weights when you drop them on concrete... Get to know the sound, and sort through them before you melt. Or keep the temperature low enough to barely melt the lead weights, and spoon everything else out...

Also, you didn't tell us about the load and gun you're using to push those 9mm boolits, or if you're sizing them after you cast... With cast boolits, all the details matter... And I've read in this forum that many guys find 9mm the most difficult to use with cast boolits... I don't shoot 9's, so I can't verify that... You may want to read about other casters' experiences (successes and failures) with 9mm as well...

[Yodogsandman]

I size both before and after powder coating.

[45 2.1]

You've received many thoughts here. Some are on the right track and some are running on someone else's road. Basically lead/tin alloys do not age harden if pure unadulterated metals are used...... unfortunately, most metals are not pure and contain other scant parts of other metals in them. This can also be said for any alloy out there not made of certified pure materials. Lead/antimony/tin alloys will age harden and increase in diameter also. Arsenic usually occurs in trace amounts in these mixes and it is a prime constituent in producing hardness, even in very small amounts. Age hardening is just that... the alloy hardens as it ages..... from dead soft at casting to greater harnesses as it ages. Aging alloys don't stop hardening for quite a while. This depends entirely on just what percentage of each alloy constituent is in the mix. Change the mix and the hardness and time till it hardens up change also. Generally it takes a little over two weeks for air cooled, water dropped or oven heat treated alloy to reach a point where your results are somewhat consistent. More aging time is always better for accuracy. I recommend you get a hardness tester and learn this for yourself.

[JonB_in_Glencoe]

Hello All,

I am a novice caster. In fact, cast my first batch of Lee TL356-124-TCs for 9mm about 6-8 weeks ago.
This first batch of range lead, water-dropped boolits tested at 10-11 BHN during the first 2-3 days after casting. Range results during the follwing couple of weeks were dissappointly inconsistent as about 20-25% were keyholing.

After much reading on this and other forms regarding the advisability of shooting slightly oversized bullets to address the issue of keyholing, it finally dawned on me a few weeks ago to test a subset of boolits from this initial batch that measured closer to .357. I took great care to keep all other variables (powder load, OAL, etc.) the same.

Much better results with these slightly larger boolits - no keyholing! So, I'm thinking the mystery is solved, right?

Maybe not. I re- tested this initial batch of boolits today to find them now consistently at 16 BHN! So, now I've got 2 variables (boolit diameter and BHN) where I thought I had only 1 (boolit diameter).

Question: Is it to be expected that cast boolits will harden with age as mine apparantly have? Any rule-of-thumb in this regard?

Read Chapter 3 of "From Ingot to Target: A Cast Bullet Guide for Handgunners©"
even it some of the metallurgy is over your head (yes much of it is over my head), it'll help you understand what happens with different types of bullet alloys.
http://www.lasc.us/Fryxell_Book_Chapter_3_alloySelectionMetallurgy.ht m

[wxman12]

[Quote]Lead/antimony/tin alloys will age harden and increase in diameter also. [Quote]

Yes, significant reduction in keyholing with time suggests bullet diameter has increased with time. Didn't think to measure diameter of newly-cast boolits, but will do this moving forward.

[Quote]More aging time is always better for accuracy.[Quote]

This is consistent with my limited experience with this first run.

Thanka!

[wxman12]

Be careful !!! Buckets of raw wheel weights from a tire shop will include zinc weights. If you put those in with the lead wheel weights, and the pot gets hot enough, the zinc will melt into the alloy. You don't want that... They sound different than lead weights when you drop them on concrete..

Also, you didn't tell us about the load and gun you're using to push those 9mm boolits, or if you're sizing them after you cast... With cast boolits, all the details matter...

Yes, have already sorted and find the "sound" test works well for me.

Shooting these through a Walther PPS with 3.2 grains of Bullseye and OAL of 1.145. Used the 45/45/10 lube recipe that I've seen referenced multiple times on this form. Sized to .356 both before and after lubing.

Thanks

[JMtoolman]

I know old bullet casters harden up with old age! I'm living proof! The toolman.