Okay, another stupid question

[Ian]

The tip-over trick works with brass, but the quench has nothing to do with the annealing, it just STOPS the annealing up at the neck when you get it just right. Torching the noses should work if you DON'T tip them over, just let the bullet's temperature naturalize.

Lead/antimony alloys have a "natural" hardness state based on the common bullet caster's reference of dropping them from the mould onto a towel and allowing them to air-quench in a "room temperature" environment. Further precipitation hardening usually occurs after that time, taking from weeks to months to stabilize. Tin slows the process, and depending on a lot of little details can affect the final hardness as well due to cross-linking with the antimony and precipitating dendrites of a different shape.

So we have an "as cast" toughness, an "aged, air cooled" toughness, and then we can monkey with the cooling rate from near-molten to achieve weaker or tougher final outcomes, but regardless, final BHN takes time to achieve.

I've annealed wheel-weight bullets to attempt to soften them and had good success. I did a maximum re-heat without slump and just dialed the oven back bit by bit over the course of something like an hour IIRC and finally just turned it off and left them to cool down with the unit overnight. They gained back a few points of hardness over months, but remained softer than they were simply air-quenched from the mould as cast.

Same thing with water-quenching, WW alloy will get super-hard in a few weeks and anneal some after it peaks out, but generally is very much more tough than air-quenched. This can be controlled very closely as Rick and many others have demonstrated repeatedly.

The takeaway here is lead/antimony alloy can be manipulated by the factors of rate of cooling from a near-slump state to room temperature and time. The monkey wrenches that often make us have different results from each other probably involve the presence/amount of grain refiners, specific techniques and test equipment, and really not knowing most of the time what is actually in our bullet metal.

 

[Ian]

Chris, I don't think it's physically possible to achieve the results you are after with the tip-over technique. A pre-hardened bullet, (allowed to age to full hardness I presume, as this effect is NOT immediate), with its nose re-annealed to near slump point and re-quenched, will END UP about the same hardness on nose as the base which was presumably hardened previously by water-quenching from high temperature. Temporarily the nose will be soft, just as the base was immediately after the initial whole-bullet heat treatment, but due to the rapid cooling of the nose you set the dendrite formation in motion to be very hard in a few weeks. It doesn't make any difference if the bullet was HT'd prior to annealing/quenching the nose or not, except for how hard the base will be. You can harden/soften the alloy an indefinite number of times without changing how it behaves.

 

[Chris]

If the base is in water it can't rise above 212 F. That is what the water does is keep the base cool.
Less nose above water and less nose is annealed, more exposed means more is exposed.

Yes. Keep the very hard base cool in water. heat the nose until almost slump. Tip the bullet over to arrest heat transfer.

If this works, as I believe it does, then this is an efficient method to soften noses while retaining super hard bases and driving bands to withstand the high pressures of hunting loads.

In the final analysis we need to understand, at a practical level, the effect of heat and cooling on our alloys. Again, what I am suggesting can easily be tested. I may be wrong... but this is how science gets done and it is really useful and interesting.

 

[Ian]

I'm saying it doesn't pass the logic test. This is lead/antimony/tin alloy, not copper/nickel alloy like brass, they don't behave the same. If you heat and quench the whole bullet, it gets very hard after a while. If you melt it down again and recast it, or just reheat to the critical temperature again, you can anneal it IF you air cool it, but if you water-quench again it will get very hard again. What you are saying to try will end up putting the nose right back where the bullet started before it was re-heated. Immediately, the bullet may have a very soft nose, but in short order it will become very hard by exactly the same mechanism that made the whole bullet very hard to begin with when you water-quenched it. Now, if you re-heat just the nose of a pre-hardened bullet, and allow the nose to cool gradually, it will remain softer than the base, perhaps significantly so if you can effectively separate the heat conduction from nose to base and slow-cool the nose.

 

[Rick]

Chris, you have it exactly backwards. If you heat the nose sufficiently and tip it over into water you have hardened it. Doesn't matter if it was oven HT prior or not. If you want to anneal the nose you need to heat it sufficiently and allow it to SLOWLY cool to room temp. This assuming you have an Sb alloy.

 

[Chris]

Chris, I don't think it's physically possible to achieve the results you are after with the tip-over technique. A pre-hardened bullet, (allowed to age to full hardness I presume, as this effect is NOT immediate), with its nose re-annealed to near slump point and re-quenched, will END UP about the same hardness on nose as the base which was presumably hardened previously by water-quenching from high temperature. Temporarily the nose will be soft, just as the base was immediately after the initial whole-bullet heat treatment, but due to the rapid cooling of the nose you set the dendrite formation in motion to be very hard in a few weeks. It doesn't make any difference if the bullet was HT'd prior to annealing/quenching the nose or not, except for how hard the base will be. You can harden/soften the alloy an indefinite number of times without changing how it behaves.

Well, I would test this and publish the results if my hardness tester were working. Testing will provide the answer. Surely someone may become curious to test this as there is utility for hunting loads. hard bases, softer noses.

Now I agree that IF the nose can be softened with heat per above that it will not last over time. How long the nose remains softer than the hardened base is in question and it's a good question. It may only last 90 days from what I have read... but that may be enough to get you through hunting season?

Surely someone may become curious to test this? I have no hardness tester but I could take some tempered bullets, heat the noses, and then send them to several men who have hardness testers. The results could be published here... either it works (at least temporarily) or it's ineffective.

 

[Rick]

Yes. Keep the very hard base cool in water. heat the nose until almost slump. Tip the bullet over to arrest heat transfer.

If this works, as I believe it does, then this is an efficient method to soften noses while retaining super hard bases and driving bands to withstand the high pressures of hunting loads.

Cannot possibly work unless you have figured out how to reverse the laws of physics that control a Pb/Sb alloy.

In the final analysis we need to understand, at a practical level, the effect of heat and cooling on our alloys. Again, what I am suggesting can easily be tested. I may be wrong... but this is how science gets done and it is really useful and interesting.

This is very well understood. Heat the bullet and change the crystalline structure of the Sb. Sudden cooling (by quenching) freezes the crystalline structure thus HARDENING it.
.

 

[Ian]

If the noses of a HT'd bullet were successfully annealed by reheat and slow cooling (it is well established that they can be), they may re-harden somewhat from their initial annealed state, but will never get as hard as the HT'd base provided the noses were cooled at a rate that was more slow than the base was cooled during the intial quench which hardened the whole bullet prior to the nose being annealed.

What you can expect from clip-on wheel weight alloy is an initial water-quench of something like 9-13 bhn (same as right after an air-quench), and in 24 hours can be anywhere from 12 to 20-something bhn depending on amount of grain refiners present which catalyze the dendrite forming process and make a finer, more tough grain structure from the get-go. In the end, COWW at max heat treat/rapid quench result in a final AGED hardness of something like 22-30 bhn. Air-quenched, the same alloy might settle in at 10-14 bhn after a few weeks. If the noses are successfully annealed after a whole-bullet heat-treat, we can expect that even after many months the bases will still be 22-30 (more likely about 24-27) and the noses will be 10-14 bhn for practical purposes permanently.

I'm not trying to test the hardening of lead/antimony/tin alloy, I know what will happen. All I'm trying to establish is whether or not the process the original poster asked about is practical to achieve. The results posted by another member on the first page of this thread suggest that it is, provided your bullets are of sufficient length and the water isn't too deep.

 

[Ian]

23 hours into the test and I had another look. Took one of each of the three sample batches and tested them end to end. The trend with all three is they are getting harder than right after treatment, but the noses are out-pacing the bases whereas they were identical hardness right after treating and quenching the bases.

The 500-grainers are all hollow points and the middle of the noses jumped 3.9 bhn points above the air-cooled, aged control sample while the bases are lagging behind by .6 point. The middle is now the same as the control exactly. Delta of 4.5 bhn points.

The Lee 230 is about 1.5 points softer than the control on the nose, and almost 4 points softer on the base. Multiple test points along its length show a linear difference in BHN. 2.5 points delta.

The ACE 235 has a lower delta between nose and base than the other two, being 2.5 points softer than control on the nose and 4.5 points softer on the base but also very linear. Two points delta.

Water-quenching always slows down the hardening rate but makes the bullets harder in the end. I'm anticipating that the noses will stabilize in about a week and the bases will stabilize in about three weeks, with some small change in the next few months. Hoping the bases will all be about 18-19 bhn and the noses under 14. I cannot explain why the thin HP of the nose on the big 500 grain bullets got so hard so fast, unless it's the lack of mass and the heat just sucked right out of them when I quenched the bases.

 

[fiver]

maybe I can explain it.
the key to heat treating and quenching a lead alloy is the quench.
it is the fast cooling that makes them hard.

if you heat them up and let them air cool you will return the BHN back to the normal alloy BHN.
it will be even softer for a few day's, just like a newly cast bullet, and it will return to the hardness of whatever the alloy is made up of.

now tipping them over into a pan of water will change the BHN but it will be due to the lower heat temp and the warmness of the water.
it will also be higher than the normal cast and air cooled alloy.
but lower than the oven cooked and cold water quenched base.

 

[Ian]

And it takes time to see the results. Water quenching may take weeks to achieve hardness but will be harder than air quenching even though the air quenched alloy hardens faster.

That's what's happening to the bullets I've been testing. By the 23-hour results you'd think I water-quenched the wrong end because right now they're all softer on the bases than the noses by several BHN points.

What really gets confusing is if there is a some As present and a lot more antimony than WW this may flip-flop and water-quenched bullets might get near full hardness in a couple of days and still take a week to reach the air-quench hardness, but still the water quenched ones will be a LOT harder than air quenched in the end when it all stabilizes.

 

[Rick]

The hardness/time is determined by the Sb percentage, the higher the Sb the quicker final BHN is achieved. A grain refiner such as As increases final BHN giving the appearance of a higher Sb percentage but without the added brittleness of additional Sb.

 

[Intheshop]

Bullets are pretty small,as in short....doh.I think,without being a negative Nellie,this is the hurdle.

Further,as I wrote earlier,don't discount a process that may be available during casting....vs,after the fact.

 

[35 Whelen]

I cast some of my very first bullets using magnum shot and adding tin. They came out beautiful. I tried the method of standing them up in water and a butane torch to the nose. According to my lead pencil tests they came out as planned, nose softer than the lower shank of the bullet. I have yet to test them in media for penetration and expansion, but the experiment worked for me. I also cast some of the 360-310 Thumpers of WW ,you see in my avatar to the left. Heat treated at 420 for an hour and ice water quenched. They were sized before heat treating. After heat treating they sat in containers for a couple of weeks before loading them. Wicked accurate with a nice mild load of 49 grains of IMR 4831 and two coats of BLL. After I purchased my Staebler pencil set, I once again tried softening the nose using the butane torch and water up to the crimp groove. According to the hardness testing I did...it worked well. Not too scientific, but there is a difference. Testing for penetration and expansion has yet to be done...our range doesn't approve of shooting anything but paper targets
[URL=http://smg.photobucket.com/user/1004jake/media/20161118_144151_1.jpg.html] [/URL]

 

[Ian]

But the question remains, did you test the bullets after they had cured for a few weeks to ensure that the noses STAYED softer than the bases?

 

[35 Whelen]

But the question remains, did you test the bullets after they had cured for a few weeks to ensure that the noses STAYED softer than the bases?

They seem to Ian....same pencils left no mark, then the next pencil was able to leave a mark.. I know not exact, but sure seemed as though there were no changes.

 

[Kevin Stenberg]

Ian in post #28. You put your HT bullets into the cooling pan of water for 30 seconds. Why did you leave them in the water for so short of a time? I would have thought that they would have been left in the water till they were completely cool.

 

[Ian]

No, I wrote "three seconds". In practice it was more like 1.5 to 2 seconds, just until the sizzle stopped. My thinking was that once the alloy is below the boiling point of water the quenching is done, and I wanted to minimize the heat loss of the noses so I didn't leave them in there. Maybe that wasn't the right thing to do, we'll see....remember this an "experiment".

 

[fiver]

I don't think 30 seconds is necessary.
as soon as the skin hits the water it is rapidly cooling down which is the start of the process.

I think, and it is me thinking.
that the rapid skin cooling is what starts the process, it locks the antimony throughout the boolit
and it can't migrate and lock together.
this tricks the lead into thinking it has more antimony in it than it really does.

it just takes more time for everything to mesh together [kind of like little arms of antimony spreading out into the alloy] and for it to affect it's surroundings, which would explain the time necessary for final hardness to occur.
and why we see varying [up and down] BHN's along the way.

TIN in the alloy is trying to hold onto the antimony and keeps the arms from spreading out as far.

 

[Rick]

I think Ian's experiment is quite interesting. Never did think of a quick 2 second or so base dunk in water. With nothing more than thinking out loud I think that the bases will not achieve the same degree of hardness that they could have and the noses might remain softer than they would have. Seems logical that the quenched base will draw heat from the noses and re-heat somewhat but still leave the noses softer than the base. Will be quite interesting to see the final results, will take a little time while waiting on age hardening.