The Theory of Water Dropping

[Shane Tuttle]

Alright, folks. It's time this subject matter is brought up in its own right for discussion. I figured instead of some poor innocent soul asks such an evil question, I would to get it out in the open now...

Does water dropping raise the hardness level of lead cast bullets? I've heard adamant answers of yes and no from very experienced casters. There has to be a reason why. I'm predicting a great, lively, informative, CIVIL discussion on the topic here...(Hint, Hint).

What say you?

[IllinoisCoyoteHunter]

Yes, water dropping your cast bullets out of the mold will raise the hardness (BHN). BUT, over time, they lose their hardness and will return to their "normal" hardness. As far as how long it takes to return to their original hardness, I haven't a clue. I'm sure someone with a hardness tester can test this or may have some input.

[Shane Tuttle]

This may be off the subject a bit, but may contribute to resolving the issue...

If it temporarily raises the BHN, then will the bullets reset to the normal hardness it would have when not water dropping in the first place?

[dahermit]

The bullet alloy must contain some arsenic to water harden. There are several sources of arsinic...chilled lead shot for one.
Perusing the following link will end the debate; they are the authorities that have been doing it for years.
http://castboolits.gunloads.com/

If it temporarily raises the BHN, then will the bullets reset to the normal hardness it would have when not water dropping in the first place? Yes, but be aware "temporarily", is several months.

[snuffy]

Yes and no. How's that for being neutral? Some say an alloy has to have some arsenic present to water drop harden. Others say it doesn't have to be present, even wheel weights,(WW), will water drop harden.

I just read a post somewhere that a guy said water dropping from a mold is inconsistent because you can't always get a bullet to drop as soon as the mold is opened. One that hangs up will be cooler when it hits the water. Then the need for constantly changing the water to keep it cool, is sometimes overlooked.

Those purists insist that heat treating is the only way to insure that every bullet is heated to the same temp, and quenched into water with ice floating in it. I tend to agree that water dropping from a mold is questionable as to consistency of the hardness. So I don't do it. I air cool all my bullets

[bustoff]

I have some bullets that I cast about 8 months ago that I quenched. 24 hours after quenching, hardness was 18 bhn. 8 months later the bullets from the same batch are now at 26 bhn! lead arsenic/antimony/alloys age harden while lead/tin alloys age soften. I did not compare hardness of quenched and as cast bullets so I dont know if they would age harden the same. Does water dropping raise the hardness level of lead cast bullets? from what Ive read lead/ tin alloys, no. lead/antimony/arsenic alloys ,yes. The experimenting I ve done has given me the same results,so far. The alloy used when casting the bullets I just described was 15 lbs wheel weigths and 5 lbs chilled shot. Hardness was checked with a lee hardness tester. http://www.lasc.us/ArticleIndex.htm the link will take you to some excellent reading on lead, alloys and casting. Ive only been casting a little over 2 years and this site has explained much along with the castboolit people.

[snuffy]

Bustoff, your statement that lead/antimony/arsenic alloys can be heat treated is wrong on a basic level. You HAVE to have tin present in order for antimony to alloy with lead. The more antimony is present, the more tin must be present in order for the antimony crystals to dissolve in the alloy.

Lead-tin alloys will NOT water quench harden. There must be some antimony present, whether the arsenic is required or not.

I tried to water drop harden some 175 .40 bullets from a lee 6 banger. I wanted to shoot them in a OEM glock M-22. I even went so far as to add some shot to the lead. I got the same hardness with air-cooled! One wexperiment proves almost nothing. Maybe I should repeat the experiment. To me, it was a hassle to have a bucket of water between my legs!:mad:

[dahermit]

I have found that water dropping bullets leads to inconsistent results. Some of the bullets were harder than others. For precision cast rifle lead bullet shooting/experimenting, most would agree that oven heat treating is more precise.

[Crosshair]

I have some bullets that I cast about 8 months ago that I quenched. 24 hours after quenching, hardness was 18 bhn. 8 months later the bullets from the same batch are now at 26 bhn! lead arsenic/antimony/alloys age harden while lead/tin alloys age soften. I did not compare hardness of quenched and as cast bullets so I dont know if they would age harden the same.
I just ran downstairs and dug out some 9mm boolits that I cast earlier this year, but never lubed. They tested 20-21 BNH just after being cast and now they are testing 26-28 BNH with it mostly being in the 26-27 BNH range.

These are straight WW boolits that I simply drop straight into a bucket of water. When I smelt the WW, I sort out the stick on weights. When I air cool I get about 11-12 BNH IIRC.

Clip on wheel weights have a decent amount of antimony and tin. The average composition I have found from online sources is 1/2% tin, 3-4% antimony, 1/4% arsenic and 951/4% lead. Plenty of antimony for water quenching.

[snuffy]

Wheel weight bullets will age harden without being water dropped. That is a time proven fact. Will they be harder if they are water dropped? Maybe. I'll tell you one thing, I'm NOT going to do a bunch of complicated tests to find out! Who knows if I'll even live that long?

I'm real happy with my air cooled bullets. Like I said, I find it a hassle to have a bucket of water around. The BHN's I end up with work well for my applications, with the alloys I have or create by mixing lead.

[Unclenick]

Lead and antimony or arsenic do not require tin to alloy (see attached chilled shot MSDS page for an example of a tin-free alloy of these metals). Tin makes it easier to alloy them both because of its lower melting point and because it helps the lead wet things, which is why it improves mold fill. There is actually a whole string of elements you can alloy with lead to harden it, and they cover quite a range of solubility. Thallium is the most soluble, while copper (used in hard babbit) and barium are the least soluble. In order of decreasing solubility, tin, antimony, and arsenic span the middle solubility range, with tin being the easiest to dissolve and arsenic the least soluble among the three.

Here's what some will find surprising: all these alloys and their combinations quench harden in water. What is different is how long they can hold their hardness, post quench, with the most easily soluble elements holding it for the shortest time. Lead/tin quickly moves from the quench to a large crystal form, so it doesn't hold the added hardness for a useful length of time. Adding antimony prevents the coarse grain formation for a longer period, but you still need to use the bullets within weeks or months after they reach peak hardness to take advantage of the effect. Adding a little arsenic makes it take a very long time to lose hardness, and it seems to prevent a complete loss of heat treating hardness from occurring. That is important to the shelf life of chilled shot, obviously, but to that of other heat treated bullets as well.

Randy Garrett (Garrett Cartridges) used to put expiration dates on his cast bullet ammo, but stopped after he'd found his water-hardened lead/antimony/arsenic bullets were still holding BHN in the twenties after a decade. A similar result is obtained by Marshall Stanton at Beartooth Bullets (http://www.beartoothbullets.com/faq/index.htm) who finds that his bullets heat treated to BHN 22 drop only to BHN 21 after their hardness peak, which they then hold indefinitely.

This paper (http://www.lasc.us/HeatTreat.htm) at the LASC is where I first got some of this information. It covers it in a good bit more detail.


Bustoff,

Quenched bullets typically need about two weeks for the crystallization process to reach full hardness, so your 24/hr - 8 month measuring looks like it skipped over the peak. Once the peak is passed, the hardness goes downhill. How fast depends on the alloy, as I described above. I've heard it recommended that you size quenched bullets within hours after casting so the surface hardness corruption caused by sizing is done before the final hardening really occurs, allowing that hardening to extend to the sized surface. I have not tested how truly that works out? But, obviously, if you size the bullets in something like the Lee sizers using mineral spirits as the lube, you can let the mineral spirits dry off, then oven heat-treat afterward and before filling the lube grooves.

If you have more tin than antimony, peak hardness is reported to go downhill faster than is the case when the reverse is true. The hardness two weeks after the quench is pretty easy to get to BHN 28 or more with controlled temperatures and quenching, but it's subsequent hardness loss goes slowly over time and appears to have a 1/e^t + k shape, dropping more quickly early on, and at a slower and slower rate over time; the constant, k, being the final hardness that is indefinite.

[zxcvbob]

I think you need antimony for the lead to quench-harden. Aresnic is optionally used in small amounts as kind of an antimony multiplier. Tin has very little effect on the hardness, but it does reduce the surface tension and make the bullets cast easier. Lead shot contains no tin at all because it wouldn't drop right with reduced surface tension.

Quench-hardened lead/antimony/tin bullets soften over time, and air-cooled cast bullets harden over time. I assume both eventually reach an equilibrium.

I cast bullets using unknown alloys of hard lead or soft lead. I quench them all as they drop from the mold because it's just easier.

I've studied this sort of thing in college (long time ago) regarding ferrous metals, but nonferrous act totally different. There's an article about heat-treating lead bullets somewhere at lasc.us but I don't have the link anymore.

[snuffy]

Good post Nick. I just spent a few minutes reading the LASC article by Rick Kelter. The last paragraph pretty much sums up what I said earlier;

Water quenching (dropping bullets straight from the mould into a bucket of water) will harden your lead, antimony, arsenic alloy but as the lead pot and mould temperature varies so does the final hardness of the bullets. Additionally, you get what you get (about 15-19 BHN with wheel weights). As the revolver tests proved, varying the BHN effects both groups and the velocity extreme spread. With convection oven heat treating a specific BHN range can be attained and variation is held to a minimum.

He also stated that too high percentages of tin makes a bullet/alloy age soften quicker. Which goes along with the statement that lead-tin alloys age soften in 2 DAYS! But it will quench harden, you just have to cast in the morning and shoot that afternoon!:rolleyes: That's two things I learned today, so today's not a loss!

I read that oven heat treating should be done 20 degrees UNDER the temp required to start the bullet melting, or slumping. Kelter says anywhere from 460 to 420 degrees, depending on type of oven.

[bustoff]

Quenched bullets typically need about two weeks for the crystallization process to reach full hardness, so your 24/hr - 8 month measuring looks like it skipped over the peak. Once the peak is passed, the hardness goes downhill. How fast depends on the alloy, as I described above. I've heard it recommended that you size quenched bullets within hours after casting so the surface hardness corruption caused by sizing is done before the final hardening really occurs, allowing that hardening to extend to the sized surface. unclenick, it seems to me that the peak hardness would not be as important as the hardness after things have stabilized, but I guess that depends on a persons shooting habits. I have also read the same thing about sizing quenched bullets and that was what I did. When I decided to try quenching I was just curious. I write most things down so I can keep track of what works and what doesnt, that was how I was able to keep track of the changing hardness values. So far Im happy with quenching as its not a inconvience. snuffy, I dont know if the info from the lasc website is 100% fact but I lean toward believing it. I dont believe my statement was wrong at a basic level, read some of the articles by Glen Fryxell. Also quenching or heat treating bullets is not for everyone and I certainly am not suggesting you try it. [QUOTE]Bustoff, your statement that lead/antimony/arsenic alloys can be heat treated is wrong on a basic level.

[GP100man]

I have some old (don`t know did`nt date em but me thinks 3 1/2 yrs) that i have to lube em before they`ll go into the sizer.

purty sure wheel weights & tin.
i`ll check bhn in the morn & post back .

[Unclenick]

Bustoff,

I only meant to point out that the time lapse between casting and your first measurement, then the subsequent long time lapse before the next measurement made it appear the bullets kept getting harder the whole time. I'm suggesting they probably were even harder about two weeks after casting and were already coming down when you measured the BHN 26. Some folks have reported peak hardness in the 30's if they got their heat and quench timing right.

[sc928porsche]

Lead oxide is much harder that lead. As lead sits the surface starts to oxidize and thus the harder reading. You may not be able to see the oxidation, but it is there nonetheless.

[snuffy]

Lead oxide is much harder that lead. As lead sits the surface starts to oxidize and thus the harder reading. You may not be able to see the oxidation, but it is there nonetheless.

The time-hardening is due to the slow change is the crystalline structure of the lead alloy. Lead oxide IS harder than it's parent metal, but I seldom see my bullets oxidizing, because they all have a coating of lube on the sides. If I leave bullets un-lubed, or as cast, I do see a layer of oxide all over the bullet, but it takes several YEARS

[Rangefinder]

After much debate and building curiosity, I decided to try it. Using the same ingot for all pours, I melted it and ladle poured the entire thing alternating between air-cooled and water-drop for the entire ingot. Once all the casts had settled to ambient temperature, I checked a few of each. Now bear in mind I don't have the little attachment for my press to accurately check the bhn specifically, it was more just a simple experiment of "ok, my thumbnail gouges this one, and I can barely make a mark on that one" type of thing. So I can't give you an exact difference between the two. I can say without a doubt that the water-dropped casts were SIGNIFICANTLY harder than the air-cooled casts, to the point that I really couldn't scrape a mark in them with a thumbnail but could put a noticable groove in the air-cooled. They are both from the same ingot melted in a clean pot and alternated throughout the entire run. Water-dropping has me sold. The ingot was nothing more than WW's. No additional alloying on my part.