Boolit hardening

[Thumbcocker]

Two questions:


1.) Will fresh cast boolits continue to harden if they are sized and lubed?

2.) Can fresh cast boolits be sized, lubed, and loaded and still harden in the cases?

I have a batch of boolits cast up Friday and would like to lube and load them. I will not be shooting them for several more days but I will have time to load them this weekend.

Alloy is acww.

Thanks.

[Harry O]

My experience is that hardened lead/tin/antimony bullets (those dropped into a tub of cold water directly from the mould) don't harden immediately. I make a point of sizing and lubing them immediately after casting. It is much easier to do right away than waiting until after they harden ( I have tried it both ways).

I have not done a check to see if they would have hardened more if I had not sized them first. However, I do know that they do continue to harden after being sized (it usually takes a week or two to get to maximum hardness).

I have no idea if they would harden in the bullet case, but I don't see why not. The bullet doesn't know if it is in a box waiting to be loaded or in a case after being loaded.

[williamwaco]

The hardening is a function of time and is not related to any other factor.

It also has nothing to do with whether you can or should or should not load them.

Here is my rule:

If they are cool enough you can hold them in your bare hand, they are ready to size, lubricate, load, and shoot.

[462]

In addition to age-hardening, boolits cast of wheel weights (antimonial lead) will grow fatter, over time.

Last week, I was loading some Lyman 429421's that were cast, air cooled, sized and lubed about two-years-ago. A dummy round would not chamber, and the boolits had to be re-sized.

I don't know the minimum amount of time for the fattening process to take place.

[madsenshooter]

Minimum fattening time depends on the nutrient content of the feed, or lack thereof.

[357shooter]

Here's a chart from a test on sizing changes for 357 magnum 158 (maybe 168) grain bullets. The blue line is unsized and unlubed. The green line is lubed and sized, hope this is helpful:

[Three44s]

First there was "age hardening" ...............

................ now, there is "age fattening"?


Oh well ........... if it was easy, everybody would be doing it!

(Personally, I've got that age fattening down to a SCIENCE!!)


I believe I have read that the hardening runs to about 2 weeks ..............?


Three 44s

[cbrick]

1.) Will fresh cast boolits continue to harden if they are sized and lubed?

2.) Can fresh cast boolits be sized, lubed, and loaded and still harden in the cases? Thanks.

Yes, size, lube & load them. Sitting in a box or in a cartridge case won't change the metallurgy, they will still age harden the same.

It's the percentage of antimony in the alloy that will determine the time/harden curve. A 2% Sb alloy will age harden much slower than a 6% Sb alloy.

Last April I cast 500 RCBS 35 caliber 180 Gr silhouette bullets, after casting they were sized/checked without lube and then convection oven heat treated. As I am ready to use them they get lubed in a die .001" larger than the die that sized them. They have not grown any amount in this time worth noting, if at all it's a matter of a tenth or two.

Rick

[geargnasher]

Two questions:


1.) Will fresh cast boolits continue to harden if they are sized and lubed? Yes, provided they contain at least a small quantity of antimony.

2.) Can fresh cast boolits be sized, lubed, and loaded and still harden in the cases? Yes, can and will. Something else they'll do, like 462 pointed out, is grow as they age.

I have a batch of boolits cast up Friday and would like to lube and load them. I will not be shooting them for several more days but I will have time to load them this weekend.

Alloy is acww.

Thanks.

ACWW usually take at least a week to get to 90% of their full hardness, and about 95% after two weeks. After a couple of weeks they usually stop growing, too, seems to be related to the age-hardening process.

Things that could be a problem with sizing and loading "green" boolits are primarily chambering problems down the road and possibly leading issues if the soft, "green" boolits are swaged undersized by the brass as they are seated.

Gear

[44man]

ACWW usually take at least a week to get to 90% of their full hardness, and about 95% after two weeks. After a couple of weeks they usually stop growing, too, seems to be related to the age-hardening process.

Things that could be a problem with sizing and loading "green" boolits are primarily chambering problems down the road and possibly leading issues if the soft, "green" boolits are swaged undersized by the brass as they are seated.

Gear

Correct!
My .476" boolits will expand to .478" with time. I have to size again and it has no affect on accuracy. I never load "green" boolits. I water drop to speed hardening and growth. It does me no good to size right away.
Bill Ferguson says to size within 1/2 hour of casting but it does nothing about expansion.
Soft, just cast can be sized by brass but I can't see lead expansion pushing brass open.
I cast, let the boolits age and then lube and size but I size at the very least to fit the gun.

[cbrick]

ACWW usually take at least a week to get to 90% of their full hardness, and about 95% after two weeks. Gear

Can't say that as an across the board all inclusive statement. The time curve is completely dependent on the Sb percentage. If you have exactly the same Pb/Sb/Sn alloy for each casting session you could make a blanket statement about the time/hardening curve. Many casters don't have the same alloy two casting session in row. For most cast bullet shooting such as low pressure/velocity short range shooting it's not really all that important to know an exact age/harden curve. As pressure/velocity, distance and the need for accuracy increase it can become increasingly important to know and understand the time curve if you wish to repeat good groups.

I have an alloy that air cooled or HT reaches it's limit in about three days. As WW becomes harder to impossible to get I will be using more and more of this alloy. That alloy is 6 BHN Pb that I currently have about 800 pounds of, Roto Metals Super Hard and 2% tin. A WW clone with a consistent and known Sb percentage of 3%.

If you want a known age/harden time curve you must have a consistent Sb percentage. 3% or 4% Sb will give you a known age/harden curve of about 3 days, lower Sb such as I suspect most current WW of about 2% or even less will up the aging time to about 2 weeks. I use 2% Sb as a max assumption for todays WW based on testing the age/harden curve.

Rick

[geargnasher]

It wasn't an "all inclusive" statement. I said "usually" and "at least". I've been using all manner of COWW for years and there has always been a big difference between the 3-day hardness and the seven-day hardness.

The timeline of age hardening also has a whole lot to do with the presence and content of grain refiners. Arsenic, sulfur, copper, etc are grain refiners and their presence will drastically affect the timeline/total amount of hardness reached, and the amount of hardness added by heat treating.

Thumbcocker asked about ACWW, and even modern weights take at least a week, two is better, to be shootable at my house.

Gear

[cbrick]

Thumbcocker asked about ACWW, and even modern weights take at least a week, two is better, to be shootable at my house. Gear

No, especially modern WW. That's why I said this . . .

I use 2% Sb as a max assumption for todays WW based on testing the age/harden curve. Rick

Arsenic as a grain refiner will be present in WW, a good deal of other possible grain refiners such as copper should be removed with fluxing with sawdust. Any other grain refiner such as sulpher should have but minor effects beyond the As.

This leaves the primary cause of variation in the age/hardening curve the percentage of Sb. Think back to the good old days when any WW alloy would reach peak hardness in 2 or 3 days. Yep, the good old days when the percentage of Sb in WW was much higher.

Rick

[ColColt]

Assuming all this, I have a box of 255 gr loaded rounds for the 45 Colt I loaded probably 20 years ago. I sold that particular 45 but still have some loaded rounds. sized to .454", they must now be .458".

[geargnasher]

Assuming all this, I have a box of 255 gr loaded rounds for the 45 Colt I loaded probably 20 years ago. I sold that particular 45 but still have some loaded rounds. sized to .454", they must now be .458".

Umm, not so much. A .45 with about 2-3% antimony will only grow a half-thousandth to a thousandth over a two-three week time period, and the growth stops about the same time the hardening stabilizes.

Gear

[44man]

Umm, not so much. A .45 with about 2-3% antimony will only grow a half-thousandth to a thousandth over a two-three week time period, and the growth stops about the same time the hardening stabilizes.

Gear

True, they won't expand that much and brass will prevent it anyway. Smaller calibers expand less then larger.

[918v]

So how hard will air cooled wheel weight boolits get in two weeks? More specifically, how hard are they straight out of the mold vs two weeks later?

[918v]

I mean do they come out BHN 8 and then harden to 12, or do they come out BHN 12 and then get harder still?

[Char-Gar]

Thumbcocker... I did some tests years ago on cast bullets. I tested their hardness on the day of casting and every day there after for four weeks. I found they reached their max hardness well before the three weeks were up.

I also measured straight WW, WW plus 1.25% tin, and WW plus 2.50 tin. I found higher the tin content the less they hardened with age. The tin added to the initial hardness of the bullets a small but measurable amount. The age hardening added a maximum of 2 points Bhn the alloy.

I don't size and lube my bullets until I am ready to load them, so I can't say anything about the effect of sizing, but I strongly expect that bullets that are sized shortly after being cast will age harden just like the ones that were not sized.

I also did not measure the bullets for age expansion and it didn't matter to me as I sized just before loading.

I also would expect bullets to age harden whether or not they loaded in cases.

While age-hardening can be measured, I have not found the difference to be significant in terms of accuracy or anything else import. There can be significant differences in accuracy produced by various alloys, but I have not found age hardening to be an issue.

I just don't cast, load and shoot on the same day. I let the bullets rest for at least a week or two before I use them. For me age hardening is more a theoretical than practical issue.

918V... There is so much difference in initial hardness of WW that there is really no way to predict, what the bullet will measure as cast or after hardening. There are some ball park numbers but you are talking some very specific numbers. I would expect age hardening to add half or less to your numbers above. i.e. Bhn 8 hardened to 9 or 10.

This is as close as I can get to on point answers to your questions.

Good shooting...

[918v]

Yes, but when we're talking about the ballpark hardness of WW, is that measured straight out of the mold, or after they are fully hardened.