A question for the gurus...........

[HABCAN]

In anticipation of our coming shooting season, I have cast many hundreds of boolits over the winter of water-dropped wheelweights. Presumably, over time, they have become 'harder'. If I now size them as needed for different guns' requirements, this will 'soften' them, or so I read here. My question is, will they over time again 'harden'? Or should I just recast them, as I do not want to oven-treat?

This question never would have occurred to me had I not learned so much more about the art of casting from the past months here, so it's all your fault, guys! And thank you so much!

[montana_charlie]

Damn! You certainly pay attention to detail when reading, and can put two and two together like a master. Now you see the pain that causes. However, there is one tidbit that you seem to have ignored.

That was the short discussion about how antimony migrates to the center of a bullet during it's time in storage. If that means the outer surface of the projectile is (now) reduced to essentially pure lead, the portion that would be affected by sizing should already be 'danged soft' (a technical term not found in discussions of the Brinell Scale of Hardness).

This observation may induce you to load and shoot the bullets you have accumulated over the winter, but it's a gamble that only you can decide to take.
CM

[Sundogg1911]

HABCAN, No they will not harden back to the water dropped hardness. Actually water dropped boolits with soften over time and retun back to the "Native hardness" Sizing does work soften them, but the longer they set, the more they will return to the pre-water dropped hardness. just like non water dropped bullets will slowly harden back to the "Pre-cast" hardness. I'm not sure of the exact timeframe, but once they reach that point the hardness will become stable.

[HABCAN]

Thank you,gentlemen. Sorta what I figured, but it is nice to have reinforcement. I'm gonna shoot 'em: they are all still 'fingernail hard'. If there's a problem I'll report.

[Bret4207]

Damn! You certainly pay attention to detail when reading, and can put two and two together like a master. Now you see the pain that causes. However, there is one tidbit that you seem to have ignored.

That was the short discussion about how antimony migrates to the center of a bullet during it's time in storage. If that means the outer surface of the projectile is (now) reduced to essentially pure lead, the portion that would be affected by sizing should already be 'danged soft' (a technical term not found in discussions of the Brinell Scale of Hardness).
This observation may induce you to load and shoot the bullets you have accumulated over the winter, but it's a gamble that only you can decide to take.
CM

I thought one of the more knowledgable (read that EDUCATED) members said that antimony could't possibly "migrate". I also was under the impression that the time period for a hardened boolit to go to it's pre-quenched state was YEARS.

Did I miss the whole thread?

[montana_charlie]

I thought one of the more knowledgable (read that EDUCATED) members said that antimony could't possibly "migrate".
I suspect you are right, Bret. My problem is that I remember best those things which surprise me the most.

The fact that anyone would (publicly) suggest that cold antimony could 'migrate' was quite surprising to me.
CM

[grumpy one]

I suspect you are right, Bret. My problem is that I remember best those things which surprise me the most.

The fact that anyone would (publicly) suggest that cold antimony could 'migrate' was quite surprising to me.
CM

I'm extrapolating somewhat beyond my training here, but I'll offer this explanation. Antimony causes precipitation hardening in lead alloys. It's solubility falls as temperature falls, so at solidification temperature and just below that, antimony crystals form and stress the crystal lattice of the lead matrix that surrounds them. This pre-stressing of the lead has the effect of making it more resistant to indentation - in other words, harder. Because lead is subject to creep - it's true maximum stress is only a few hundred PSI, but it takes centuries to creep enough to stress-relax - the stress in the lattice slowly declines, and so does the hardness. Yes, it takes years. Meanwhile in the first year or so after heat treatment antimony crystals are still growing, forming, getting squeezed into the lead lattice, etc and this increases hardness, while stress relaxation is simultaneously decreasing hardness. Fairly obviously, lead crystals do not migrate far in the lead matrix once they have formed, but they can move microscopically to fit into the lead matrix better. (No, they cannot move to the bullet core, which would be a macroscopic movement.) Whenever the lead matrix is worked - for example by sizing - it yields completely and stress-relaxes, negating the effect of the precipitation hardening. So, to predict the hardness pattern within a hardened then sized lead bullet you have to know which areas of it have yielded during the sizing process. This seems likely to depend on the bullet design, the sizing die design, and most of all, on how much you sized it down.

[leftiye]

Size em foist - THEN heat treat em.

[454PB]

I agree with Leftiye. However, if you want to use the quench-from-mould method, size them immediately before they begin to harden. I have some WCWW samples I've been running a long term test on, and they are over a year old now. They are still at 26 BHN.

[felix]

You might increase your accuracy if you let the boolits get hard enough to make them size straighter. The longer the boolit, the more the delay before sizing becomes a benefit. Once sized or swagged into exact throat fit, then an oven treatment can be used to re-harden the bearing surface. Do NOT oven treat boolits with gaschecks because the alloy might/can/will crack upon rapid cooling at the crimp area. I know!!! Not worth this trouble unless you have a BR gun, and then it is questionable because of the alloy used that day might not appreciate the difference, or the amount of "sizing" was not significant enough to matter on target. ... felix

[Bret4207]

Thanks! I thought all those years of boozing had finally caught up with me and I'd lost my mind.....well, more of it anyway.

All this does is increase my preference for shooting "as cast" boolits. If it'll fit in the throat, shoot it and see if it works.

[MtGun44]

Not sure about heat treated antimonial alloys, but eutectic solder
(63-37 tin lead) will creep in days to nearly eliminate stresses in soldered
electronic assemblies. I do stress analysis on these things and this
is an important trait, saves a lot of electronics from failure during
thermal cycling since it starts out essentially stress free at room temp
rather than with a bunch of locked in stresses due to cooling down
from soldering temps.

I would tend to think that internal stresses in any lead alloy would
creep away, down to a few hundred psi in a similar time frame, but
have no facts to back that up. I do not think internal stress is the same
thing as the hardness.

I have also read that the time to lose the hardness imparted by heat
treating boolits is years, like Bret said.

Bill

[Bass Ackward]

My long term test is from 1991 with North Carolina WWs that were 12 BHN when air cooled. WD they ranged up to 28 BHN.

One year later they were 20 BHN.

17 years later they are still a uniform 20 BHN and holding.

I figure that if you keep boolits around longer than that without remolding them, you just don't shoot enough or have too much lead. :grin:

[Lead melter]

OK, now I'm really confused! If we assume that plain lead boolits can be stable up to say...1300 fps, WW boolits stable at about 1600-1800 fps, and harder boolits of linotype stable at about 2000 or more fps with BHN readings of 5-6 for lead, 10-11 for WW and 22-24 for lino [depending upon whose scale we use] what would be the purpose of heat treating them? I'll also assume that nose, fit, diameter and so forth have been considered.
Not trying to be a smart guy, but if the boolits do harden over time, as some have posted here, the advantage of heat treating or softening, with all the more work involved, seems to be lost on me.
I can see the allure of casting a soft nose with a hard shank, but would a softer overall boolit not perform as well, even after it has had time to harden?
I'll give a case in point. About 5 years ago I cast some Lee 457-405-RN/FP from an alloy of 2/3 lead and 1/3 lino. As near as I could figure, this would give a BHN of 15-16. Last year I shot one from my H&R Handi from a range of 10 feet into a 7" thick chunk of green burr pine. Total penetration, plus about 12" of North Carolina hard dried clay. The load was 27 grains AA-5744. The boolit nose simply "set back" to a max diameter of .490" In my opinion, this was plenty hard enough, and maybe too hard, for most any critter walking...with no extra work involved in heat treating, sizing after hardening, etc.
I'm not trying to step on any toes, nor argue the point, but just wondering what the point actually is.
Maybe I'm just in camp with Bret...cast, size, load, and shoot.
Somebody set me straight.

[felix]

High tin content will indeed creep causing spikes to rise away from the circuit board "wire". These spikes will indeed cause a short should two spikes touch from two different "wires". However, spiking does not occur when using tin in augmentation amounts, rather than in primary amounts. 100 percent tin is definitely a no-no for circuitry, and has been used because of the "no-lead" laws. If a computer goes bananas after a year or two, chances are good the boards were manufactured with "tin" wire. Nothing to do but trade-in the computer pronto. They cannot be fixed for the most part.

There is no point in trying different lead compositions without a reason for doing so. Must have objectives, and be mean enough to hold true to the supposition in your head until throughly defeated as typically indicated by crying "Uncle".

... felix

[HORNET]

Lead melter,
The idea with the heat treating is to get a softer and usually less expensive low antimony alloy up to the hardness level of a much more expensive high antimony alloy. sometimes this is dine for reasons of economy, sometimes because there's no available supply of high antimony alloy, and sometimes because the objective is to get the hardness necessary to withstand the firing stresses without the brittleness associated with high antimony level alloys.
Some on here routinely water quench everything, some prefer to oven heat treat claiming more uniform hardness levels, some prefer to avoid the hassles and just alloy to the desired hardness.
Almost as controversial as bottom-pour vs. ladle casting at times. It depends on what you're trying to do.

[C.F.Plinker]

I need some education too. In Dennis Marshall's article in the NRA Cast Bullets book he states (middle of page 128) that the work softening due to sizing occurs only to a depth of .001 - .002 inches. This is only 1/4 to 1/2 of the depth of the grooves on my pistols. Why wouldn't the tops of the lands bite into the harder lead where the strength is and allow the softer lead (at the bottom of the grooves) to obturate and prevent gas cutting and the associated leading. This assumes that the bullet is sized to the groove diameter. If the bullet is sized to .002 or .003 above the groove diameter then wouldn't the hard part of the bullet extend all the way out to the bottom of the lands?

[felix]

Work softening occurs only down to the extent/depth where "spring back" operates at 100 percent. Marshall is correct, again! Naturally, if the boolit is enlongated by significant sizing, then that would be more than 0.001 or 0.002 in depth, and very well could be through the entire boolit. ... felix

[cbrick]

Takes years to soften enough to make much of a difference. I did a completely un-intentional 10 year hardness test on oven HT boolits. A couple of years ago I was cleaning out the cabinet under the loading bench and discovered a few box's of boolits marked with date, alloy (WW+ 2% tin) and heat treated to 30 BHN. After 10 years I thought they would be putty but they BHN tested 26. So yes, they age softened but . . .

Heat treat rather than use high antimony alloys.

Hornet explained it well. I use WW because of it's much lower antimony percentage. Most of my shooting is on steel targets and a lower antimony percentage is a very good thing. I oven HT the alloy for the top end revolver loads I use. Best of both worlds, I get the needed hardness but without the brittleness of higher antimony alloys that are harder to come by. I also get the consistency of 800-900 bullets from the same pot of alloy, heated to exactly the same temp and quenched in exactly the same temp water.

Work soften quenched boolits by sizing.

Probably some but how much would depend on how hard they are in the first place and how much they are sized. Also consider the load they will be used in or, given the original BHN does any minor softening leave them still strong enough for the application? HABCAN, I think I'd shoot at least enough of them to test it in your loads and firearms and see. Chances are they will be fine with no need to re-cast them all, unless of coarse you're only looking for a reason to cast more? [smilie=1:

Rick

[Lead melter]

HORNET,
Thanks for clearing that up for me. It seems like the cost monster is rearing its ugly head again.