Lead hardness depends on temp. of water for heat quenching?

[oldandslow]

Greetings casters, 4/9/13

As I have recently progressed from air-cooled boolits for pistol shooting to water-quenched boolits for rifle shooting I noted some moderate differences in BHN depending on the temp. of the water.

Alloy- ww with 1-2% tin.
Boolit mold- Accurate Mold 310-180 grain F.
BHN tester- Lee. Diameter measured in at least two different axis.
BHN air cooled 24 hours after casting- 8.2
BHN for 70 degree water cooled boolits after 60 minutes in oven at 465 degrees (measured with oven therm.)-
16.6. (48 hours after quenching)
BHN for ice water (pan in freezer where had to break ice from surface to drop boolits)- 465 degrees for 60 minutes- 20.9. (48 hours after quenching).

So it appears that I can get a 25% increase in BHN hardness (16 to almost 21) simply by dropping the boolit into ice water. Is that what others have noted or does everyone just go with plain tap-water quenching?

best wishes- oldandslow

[cbrick]

It's possible that as you cast and drop the boolits into water the mold temp varies and that can give you some variation in final hardness. I played around with oven heat treating several years ago and wrote the linked article. I too achieved a higher BHN with iced water when using a conventional cook oven to heat treat but that difference disappeared when I started using a convection oven.

Heat Treating Lead/Antimony/Arsenic Alloys (http://www.lasc.us/HeatTreat.htm)

One of the things I learned was that it's a rare boolit that needs to be as hard as can be achieved via oven heat treating. 18 BHN is as hard as I go anymore and that's for a high end long range revolver match load.

Rick

[44man]

I suppose cold would add some hardness. A lot of my winter casting is in the garage and the water in my bucket is darn cold.
But I stopped worrying about actual hardness long ago. Water drop does what I need and I never seen any difference at the targets if there was any hardness difference. I stay away from the tester and scales.
As long as the fliers are gone (I get them with air cooled.) I am happy.
Air cooled is good enough for most shooting but after putting 3 shots in a ragged hole, there always seems to be a few out.
The main reason I water drop is the small space on my bench and moving boolits on the rags so I have room for more. I have to keep putting them in a box too and have grabbed some darn hot ones. No, I don't wear gloves!
Beyond that, it doesn't seem to matter if a boolit is 16, 18 or 20 BHN. All I worry about is making the boolit tough enough to take the rifling.
The day I sort by hardness and weight will mean I have nothing else to do! I would rather spend time here with friends. [smilie=w:

[MBfrontier]

Thanks for the article cbrick. I read it on lasc.com about a week ago and heat treated two batches of 9mm bullets two days ago. I am trying 450 degrees for 60 minutes before water quenching. I'll try loading and shooting with them after a few more days to see how it works out. I like that all of the bullets in a batch would be heat treated the same using this method. Don't let my wife know I used her Breville convection oven!

[cbrick]

Don't let my wife know I used her Breville convection oven!

I'm dialing her cell number right now . . . :mrgreen:

Rick

[44man]

I'm dialing her cell number right now . . . :mrgreen:

Rick
You devil you! [smilie=s:

[runfiverun]

the second hand store is your friend.
or buying new stuff for her, so you can have the old stuff.

[Bigslug]

Hmmmm. . .

You know the old hand-cranked ice cream makers that you would add rock salt to the ice for the purpose of bringing the temperature of the water down below 32F?

I'm wondering. . . make some super-saturated salt water, stash it in your freezer until is starts getting slushy, and see what that does as a quench medium.

[RickinTN]

Not sure I would want the salt in my rifles' or handguns' bores. I'm thinking 18bhn is probably plenty for my use as CBrick says.

[Bigslug]

Well, yes, there would have to be a rinse cycle involved.

[runfiverun]

or just go get some snow off the front lawn.
I would do a long term test of the from the mold into tap water and into the ice depths.
the reason the boolits get harder is because of the rapid cooling.
if you go from as hot as possible to as cold as possible as fast as possible you get them as hard as possible.
you'll have to play with your alloy's make up to get them to the max hardness but I would make a guess at something like .3% tin .25% arsenic and 5% antimony, heat shocked from around 500-f into slush would be right near maximum bhn as possible.
mid to high 30's would be my guess.

[1bluehorse]

Have you checked the BHN after a couple weeks ?? Do they not get harder over time (up to a point) after water quenching or do they (bullets) stay pretty much the same after, say, 48hrs.

[Harry O]

My experience is similar to yours. Dropping a bullet with antimony (and presumably arsenic) into water will harden it quite a bit (over Bhn 20 to nearly Bhn 30). The colder the water, the greater it will harden. The problem is consistency of the hardness. Dropping a bunch of cast bullets into cold water will heat the water up. By the end of a casting session, the water is warm to the touch. That means bullets cast at the beginning of a session are harder than ones cast later in the session. The difference can be quite large, which is one reason why I usually don’t drop bullets into water.

There seems to be much less variation in hardness when dropped onto a towel to air-dry, but it will not be as hard. Lack of hardness is not a major problem since I rarely use more than Bhn 15 anymore. The majority of the bullets I use is Bhn 11. My CAS loads are Bhn 6 or 7.

Another reason I don’t water-drop cast bullets anymore is that the hardness decreases with age. When I cast bullets I usually cast up a bunch (20 to 40 lbs worth stored in a sealed ammo box) and store them unsized and unlubed. When ready to reload, I will size and lube enough for what I plan to load. I still have some cast bullets that were originally cast 20 odd years ago. I don’t know the average age of the bullets I use, but I would guess maybe 5 years from casting to shooting. That means that if it had been hardened when I cast it, it would be soft again by the time I shot it. That introduces another (very important) variable in getting a good load.

The hardness of bullets that are air dropped changes very little over the years.

[cbrick]

That's partially correct Harry, heat treated boolits do age soften over time but it's actually much slower than many think. I oven heat treated boolits to 30 BHN and 10 years later found them stashed away under the loading bench, they were 26 BHN.

One of the things that effects rate of age softening is the tin percentage, the higher the percentage of tin the faster they age soften plus a higher tin percentage can limit the amount of hardening that can be acheived. The percentage of antimony will effect the speed they age harden, a 5% Sb alloy will reach final hardness quicker than will a 2% Sb alloy.

Rick

[rnhathaway]

At what point does the lead get too hard that it becomes brittle?

[Harry O]

One of the things that effects rate of age softening is the tin percentage, the higher the percentage of tin the faster they age soften plus a higher tin percentage can limit the amount of hardening that can be acheived. The percentage of antimony will effect the speed they age harden, a 5% Sb alloy will reach final hardness quicker than will a 2% Sb alloy.

Rick

Like you, I have found that the more the antimony, the quicker it hardens. However, I use more tin than many who post here and try not to use less percentage of tin than I have of antimony. I have plenty of tin from garage sales and estate sales that my wife goes to (from solder that is sold cheap--50lbs or so) and I use it generously. Tin makes everything else in casting easier.

I know from reading here that a lot of others use far less tin than I do. That may be why mine seem to soften quicker than you mention. I thought it might be because the more antimony used, the quicker the bullet softens, but never did any testing to find out. Since I use more tin whenever I use more antimony, that could be the reason it softens quicker instead of my original theory.

However, mainly because I don't hardly ever use bullets over 20Bhn anymore, I don't bother to quench harden them any more.

[FAsmus]

Gentlemen;

My technique for extra-cold water for the quench is simply to cast in the winter when things are nice and cool - say 10 degrees or less out in my unheated casting shed.

As other members have mentioned I find that HT bullets perform more consistently - so I water drop as I cast.

I say nix on salt saturated water! Simply mix up the typical glycol/water we all use in our car's cooling systems! This works perfectly, keeping the quench medium liquid as long as you care to cast out there. It washes off with one pass through fresh water and you're right back where "normal" water quenching winds up: Wet bullets that only need drying out and aging for 24 hours to be loaded and fired.

This winter I built up enough inventory to last all this coming summer. No problem; I simply cast when it is too crummy outside to do anything else.

Good evening,
Forrest

[FAsmus]

Harry O:

Back before I started using a glycol mix I used to go out to cast and break the ice off the surface of my quench bucket. ~ Then I'd go to casting bullets.

It was cold out there of course but I still expected that the hot bullets would heat up my water at least enough to melt the ice that remained in the bucket and stuck to the sides. ~ Not so!

What actually happened was that more ice formed in the bucket as I worked! The ice around the edge of the water stayed there and, if anything, grew out toward the center. (Hard to say exactly since the action of dropping always kept things moving to some degree.)

I was puzzled by this until I realized that water has much greater heat index than lead. That is to say that it takes many more calories to heat up a pound of water than it does to heat up a pound of lead - this works in reverse too, making it clear why the water never heated up at all, even with 4 - 500 degree bullets dropping into it at two 190 grain bullets per pass of my mold..

Good evening,
Forrest

[runfiverun]

propylene glycol would be much better than ethylene glycol.
especially in the severe cold or if the dog drinks it.

if you are using a 5 gallon bucket you are gonna have to put a LOT of BIG boolits in it to heat it up.
I use 1/2 gallon of water and will drop @ 300 435 gr 45/70's before the water warms up much.
I stop and empty the pail and put in new water anyway at this point.

[waksupi]

I've not read all of the thread, so hope I'm not repeating something.
I took a day a few years ago, and heat treated boolits in a toaster oven, at 20 degree variations. I found you can make nearly any hardness you want up to around 24 Bn by varying the temperature of the oven. If you need anything harder, you need to add shot in for arsenic content, and then you can easily take the hardness up to around 30-32. This is with wheel weight alloy.
Why screw around with potentially dangerous, and inaccurate methods?

[cbrick]

At what point does the lead get too hard that it becomes brittle?

Your confusing hardness with brittleness. Boolits can be made hard without adding brittleness. The brittleness comes from antimony and as the percentage of Sb increases so does the brittleness, going over about 5-6% Sb brittleness increases accordingly. A Pb/Sb alloy can be made harder than the percentage of antimony would suggest by quenching or oven heat treating without adding any brittleness as long as there is antimony present. Other elements such as arsenic further increase the effect of quench hardening.

Rick

[44man]

At what point does the lead get too hard that it becomes brittle?
It is the alloy, not how you cast. Even a 50-50 WW and pure alloy will harden enough to take rifling but might need a GC if shot fast.
This does NOT change the ductile properties of the alloy enough to worry about.
Air cooled WW's and water dropped act the same on deer, etc. For me it is only the ability to take the twist without skid and a few points of BHN just does not affect a thing.
Fooling with alloys to 30 BHN for targets has shown some boolits more accurate, it gets expensive but they are not brittle. Water dropping made them hard without going to brittle.
Now the crazy thing was air cooled WW boolits that had fliers. They were gas checked. I annealed some checks and accuracy got better! Explain that for me!
Even my PB .475 and .500 JH boolits are just water dropped WW metal. I just might have more 1" down to 1/2" groups with a revolver at 100 yards then anyone with batches of boolits that are all different BHN readings.
I am the weak link, I will never shoot as good as the boolits can.
You can read the alloy at the target and can change what you shoot. It really is your job just like working loads.
Reading the alloy is like reading a primer. Not easy at the start because you will think the powder charge and the worst is to ignore the twist.
I just can't bring it all together, too many variables.

[cbrick]

I annealed some checks and accuracy got better! Explain that for me!


Probably because the annealed checks fit on flat and square better than the non-annealed checks. I don't anneal checks but for all my long range revolver loads I do "size" my checks and for the same reason as annealing . . . flat against the boolit base and square to the boolit when crimped. The higher the velocity AND the longer the range the more important the base of the boolit, PB or GC is flat and square.

Rick

[btroj]

I water drop. With some bullets it can get pretty darn warm. For handgun bullets I don't worry as the hardness differences won't show up in the shooting I do.

I am sure that someone will find a way to connect a chiller and a PID to ensure the water temp stays within a 2 degree window. It won't be me.

[44man]

Probably because the annealed checks fit on flat and square better than the non-annealed checks. I don't anneal checks but for all my long range revolver loads I do "size" my checks and for the same reason as annealing . . . flat against the boolit base and square to the boolit when crimped. The higher the velocity AND the longer the range the more important the base of the boolit, PB or GC is flat and square.

Rick
Could be but I am very fussy to fit a check before sizing. I use mostly Lee dies so the check must be right first and I seat them base first through the dies.
I can't explain why an annealed check shot better with air cooled. I found no difference with water dropped. Do they halt skid better? Does soft copper grab the rifling better then hard? I am going to experiment more with annealed on harder boolits. I have not done enough.

[cbrick]

I water drop. With some bullets it can get pretty darn warm. For handgun bullets I don't worry as the hardness differences won't show up in the shooting I do.

I am sure that someone will find a way to connect a chiller and a PID to ensure the water temp stays within a 2 degree window. It won't be me.

Variations in BHN within the same 5 shot group show up at longer ranges, the longer the range the easier it is to see the difference in group size.

For long range revolver match loads that shoot best at 18 BHN I oven heat treat, all boolits are the same temp and go into the same temp water at the same time.

A chiller and PID controller :veryconfu it'll be you before it'll be me. :mrgreen:

Rick

[btroj]

If I was shooting metallic silhouette with a handgun I would do like you did.

My fear is that people see these posts and assume that for 25 yard accuracy you need to control BHn to .1 or better. I don't think it matters for most people.

Unless you are shooting a longer range competition with an accurate firearm small differences in BHn aren't likely to matter much.

Rick, I don't even own a PID. Considered one for the pot but the cost just bugs me. Sometimes I can be just plain cheap.

[cbrick]

I put a PID on my Magma pot and what a joy to use it is. Is it a necessity? No, absolutely not. I cast for many years without one but hey, a guy just has to have his toys and that particular toy is wonderful.

Yes, long range handgun silhouette is what I shot for 30 years concentrating mostly on revolver class. Shooting 200 meter cast boolit groups with a open sight revolver will teach ya what is important. You are correct though that most people shoot 25 yards and under with handguns and at these ranges the single most important thing is that the boolit fit the gun properly. That's far more important than alloy, BHN & all the rest.

Rick

[btroj]

Too many try to take specific techniques from the competiton sports and extrapolate them to every day use.
I don't turn case necks for factory rifles but if I shot BR I sure would. This, bottom pour vs ladle, and many other things have a place in specific shooting sports. They don't need to be followed by the masses shooting everyday rifles and handguns at "normal" ranges.

Cast good bullets, use a good lube, fit them to your gun, and go have fun. Don't get wrapped around the axle worrying over things that won't make a difference unless you HAVE to.

[geargnasher]

Achieving consistency in everything is important to long-range accuracy. Method matters not as long as the results are consistent. Oven heat-treating is a simple way to achieve consistency, but most of the time I just quench and don't worry about it.

The reason my preferred method of dropping into a bucket from the mold works is twofold: For one, I've gotten pretty good at it and only drop into the bucket when I'm up to speed and the boolits are coming out the way I want them. If anything changes, a pause, fiddle with the mould, add alloy, etc. I cull the next few pours until the mould is back to the temperature it was and I'm in the "zone" again. If I were shooting competitively I would oven heat-treat. The other reason quenching from the mould works is I only do that with low-antimony alloys that take a while to age anyway. I find that if the antimony is below two percent and arsenic is low, even large inconsistencies in drop rhythm or mould temperature will ultimately yield boolits that are pretty close to the same hardness in two or three months.

Rick, I learned something today, not sure why I never put two-and-two together before, but what you say about tin percentage causing the age-softening of heat-treated antimonial alloy makes perfect sense considering how binary tin/lead alloy behaves.

Gear

[geargnasher]

Brad, I think Bass's "It only matters if it does" quote ought to be on a banner at the top of the forum. All the little tricks and details can matter, but most people's loading techniques and shooting habits will never be able to tell much difference with a lot of them. When you start crowding half MOA at long range and high velocity, then those little things matter a BUNCH.

Gear

[btroj]

Bass's words of wisdom are EXACTLY what I was think of as I typed me post.
That should be the banner at the top of the forum, it sums up everything in a simple, concise manner.

More important to me is this- if it doesn't matter then why is it being worried over?

[44man]

Now you know why I think so much of all of you.
Like Rick, I shot IHMSA and it has to be the best ever. It is going down because of cost and travel distance. That is what killed me. I would shoot IHMSA every day, it is just too good to go away.
Elmer had me shooting the .44 over 400 yards in 1956, IHMSA made me work.
Now it is speed shooting at close range and cowboy action shooting. OK, but it will also drop off. The main reason is expense.
We lose when the cost goes up. The time I spent loading and the cost to get ready plus gas and travel just broke it all.
Yet experience was learned and it still applies. How to convey to a new shooter? How to get a shooter away from 10, 15 and 25 yards?
The largest enemy we have are anti gun nuts for sure but next is expense and the Democrats will make it worse.