Got a recipe for heat treatment of boolits?

[HammerMTB]

OK, this may get me into more trouble than it was intended to get me out of.
I want some harder boolits. I typically just use WW, air cooled. This works in all my loads up to 1200FPS, and up to 1500 FPS in my 45-70. Those get PP'd at higher vels.
The rest get GC'd.
My thought is I want to push hardness up to 16-20BHN, maybe more. Is there a temp/time chart for this? Or will it be trial and error?

[prs]

The previous Lyman Handbook for cast bulllets had the methodology. Water dropping from the mold is popular. I prefer air cooling, sizing and then re-heating to near slump temp in an oven using a french-fry basket. Give it time to thoroughly soak the boolits with heat so they are all heated the same through and through and then dunk the whole basket into cold water in a deep sink. Best to be sure the "Little Woman" is not home. ;-) I have done this with WW plus extra 2% tin. Don't have a hardness tester, but they did not need ****** for sure.

prs

[RobS]

Every oven is different in regards to temps and convection ovens and normal ovens heat differently as well. The thing you need is a good thermometer so you know what's going on in the oven. The link below will give you a general starting point and the author has a chart at the bottom of the page that gives his temps used to receive certain BHN hardness.

http://www.lasc.us/HeatTreat.htm

with my convection oven I'm getting about the same BHN readings with those temps.

The cool thing with an oven is you can also anneal boolits back down to a softer BHN and it can also be used as a tool to speed up age hardening.

[onondaga]

Not all wheel weight alloys have Antimony in them and that is important for heat treatment to be terrific. But try anyway!

Drop chilling your cast bullets immediately into water will harden them a bit but the amount of hardening can vary a lot from bullet to bullet with drop chilling. Heat treating a batch at a time in an oven is very consistent for the whole batch.

I have had success with batches getting wheel weight close to where you want like this:

Put the bullets on a cookie sheet and place into oven at 350 F. for 1 hour. Have a bucket of ice water ready and dump the whole tray full into the bucket.

Some will have preferences for when to size and gas check, either before or after heat treatment. I do heat treatment after sizing/checking.

The bullets will change color, possibly a lot if they have lube on them, but this is harmless. I only tumble lube with 45:45:10 and use the lightest coat before sizing/checking then after heat treatment. Some people have good results only lubung bullets with dish soap before sizing. That is worth a try. I tumble lube them twice again after heat treatment for rifle bullets.

Different temps will give different results with the heat treatment. Ice water makes a difference too. I have melted bullets by accidentally setting the oven at 450. The temp swing of my electric kitchen oven was enough to ruin the bullets. Kitchen ovens can swing pretty far. Turbo ovens have less swing. 350F has always been safe for me and gotten good results.

Gary

[Ole]

If you use a toaster oven, err on the side of caution because there is a fairly large temperature swing in heat cycles on a typical toaster oven.

I set mine around 400F and it kicks on around 410 and kicks off around 450, but the temp lingers up to 460 before all the heat is out of the coils.

What i'm saying is you could easily slump your boolits trying to heat treat them if you're not careful.

Make sure you use a good oven thermometer.

[reloader28]

I've water dropped from the mold a couple times, but I've oven treated many times.

The oven treat seems more consistant and you can get them REALLY hard with fast results. I leave a thermometer in the oven to monitor it, but its always right with the dial on my gas stove.

For pistols, I use only straight clip on WW alloy.

I've tried 450* for 1 hour only a couple times, but I'm going to play more around that temp (420-450) cause I think it will come out close to water dropping.

480* for 1 hour gets very hard. according to the hardness tester ( I forgot the BHN) but its 40,000+ pressure.

I like oven treating over water dropping (for certain calibers) cause of the consistancy and quality control and cause I can do it at anytime for whatever gun and whichever size boolit I need.

[Dutch4122]

Alloy of 50% clip on wheelweight alloy and 50% pure lead. Water dropped into a bucket straight from the mold. Size, lube, and gas check within 24 hours after casting. Then let them sit 2 weeks to age harden. I get 22 BHN consistantly. This alloy is hard, but not brittle. Air cooled for non-magnum handgun rounds; water dropped for magnum handgun & rifle loads. Very accurate. Great performance on game.

Hope this helps, :D

[BABore]

To go a bit further than Dutch, first you need to qualify your WW's. The WW's should be sorted of all soft stick-ons. Try to smelt them in as large of batch as possible so you get some consistency. Then oven HT a small batch at 450 F for 60 minutes in a calibrated oven. Real kitchen ovens work better than the smaller countertop tin boxes. They have a more even heat, larger box size, and typically better control which all makes for consistency. When you quench the boolits it must be as fast as possible. Even if that means a towel lined bucket of water right next to the stove. Strive for 3 seconds or less from oven removal to the spalsh. Do a hardness test after two weeks. If your HTWW's are between 27 and 30 bhn, then your WW's are of similar makeup as the ones Dutch and I use.

Now, you have some options for a 16 bhn alloy. 50/50 WW-Pb will get you around 20-22 bhn when heat treated at 435 F. To get the hardness to 16 bhn you will need to run around 35/65 WW-Pb. This will result in a very tough and malleable alloy that will expand well on game and shoot good at higer velocity.

Another method is to HT your WW's at 450 F and quench. Then return them to the oven at between 325 and 375 F for one hour. Turn off the oven and don't open the door til the next morning. This will anneal or draw back the boolits from their hardened potential of 27-30 bhn to 16-18 bhn. I have some specific data at home where I did lengthy test on drawing back HTWW's. IIRC I started at 275 F and went up in 25 F increments. Hardness values were taken at removal, 2 days, 7 day. 2 weeks, and 1 month to verify things. I was able to take the WW's down in approximately 2 bhn increments. IIRC I stopped at around 16 bhn. I also ran a side test to see if I had to wait for the HTWW's to achieve their full hardness before annealing, or if it could be done immediately after quenching. My tests showed it didn't matter, so do them right away. You'll have to do some of your own testing to get the exact annealing temp for your alloy.

Contrary to popular wisdom here, if your water dropped hardness is not as hard nor as consistent as your oven heat treat hardness, the problem is not the method but the operator. The caster is not being consistent in their cadence. Inconsistent casting cadence results in inconsistent mold temperature which results in inconsistent boolit temperature when they hit the water. It has very little to do with pot temperature if your running your alloy between 650 to 750 F. Waiting an lengthy amount of time for the sprue to cool or quenching the sprue and plate on a damp rag does wonders for a textbook clean cut sprue, but sucks the heat out of the mold. Tearing a little sprue out of the boolit bases doesn't really affect accuracy to any extent. If you want consistent water dropped boolits, that equal your OHT'd ones, run your mold hot enough and at a steady pace. Use a clock with a second hand if necessary.

[sqlbullet]

Conventional wisdom and anecdotes are intriguing to me as they often don't stand up to actual scrutiny.

Couple years ago my son did his science fair in fifth grade on heat treating lead alloys. We cast 180 bullets from a 650° F pot, 180 bullets from a 700° F pot, and 180 bullets from a 750° F pot. Half of each group were water quenched. approximately 50 bullets were cast at the start of each group to determine how long to harden the sprue, and subsequent casting cadence was counted aloud.

Once complete, lots of 10 were drawn creating three samples of 10 in each temp range that were air cooled, and three sample lots of 10 that were quenched, for a total of 18 sample lots. One lot of air cooled and quenched in each range were reserved as control, one lot of each was subjected to a low temp treatment of 350° for one hour then air-cooled, and one lot of each was high temp treated to 450° for one hour in a wire basket, then quenched.


Drop chilling your cast bullets immediately into water will harden them a bit but the amount of hardening can vary a lot from bullet to bullet with drop chilling. Heat treating a batch at a time in an oven is very consistent for the whole batch.

Cadence is critical, but in our tests, the adjusted deviation was half as big for the quench bullets as it was for air-cooled, high temp oven treated bullets (.67 vs 1.45). The adjusted deviation for the quenched and high temp oven treated bullets was better but still more deviation than quenched alone (.71 vs .94). The raw deviation on the quenched bullets was 1.05, but the raw hardness average on the quenched bullets was 9 points and 8 points higher. The adjusted deviation is once the hardness is adjusted to the same range average.

This was consistent for all six sets of high temp treated bullets versus the quenched bullets.


if your water dropped hardness is not as hard nor as consistent as your oven heat treat hardness, the problem is not the method but the operator.

The testing my son did definitely supports this conclusion. If you cast from a consistent pot temp, with a consistent cadence, you can achieve bullets just as hard or harder and as consistent or more consistent than you can through oven treating.

The only potential disadvantage of quenching from the mold is the conjecture that subsequent sizing will work soften the lead. I contend that this softening is inconsequential, but I need another child to get to science fair age to have an excuse to test.

[onondaga]

The only potential disadvantage of quenching from the mold is the conjecture that subsequent sizing will work soften the lead. I contend that this softening is inconsequential, but I need another child to get to science fair age to have an excuse to test.

Yea, We have seen some discussions on this! Some consider it very consequential. That is why I changed to heat treat after sizing. That does leave the lube problem. I am going to try soap like somebody here mentioned for sizing and then rinse them before heat treat and tumble lube. Worth a try if they will pass through the sizer OK. My concern with the soap is that it may effect the bond of my lube at HI-Velocity, little changes can have big consequences at HI- Velocity and every thing is working right now for me.

The constant cadence is also what gave me grief, caused hardness test fluctuation and changed me over to oven heat treat. But generally I have changed to just getting the alloy to drop at the BHN I want and am much happier. Fortunately I got a couple hundred pounds of nice Linotype last year and It alloys with my other inventory well to get me what I want right out of the mold .

I have gotten over 20 BHN by drop chilling wheel weight cast bullets, but man you gotta be fast and stay fast for the whole batch. If the bullet comes out of the mold on the first tap or if it comes out on the sixth tap makes a real difference in my BHN tests when drop chilling. So, mold performance and casting technique has to be perfect and fast. I am too old for that----I'll use the oven.

Gary

[AZ-Stew]

Read the posts in this thread for my experiences (successful) in finding a way to do oven heat treating on the cheap:

http://castboolits.gunloads.com/showthread.php?t=42870&highlight=toaster

Regards,

Stew

[HammerMTB]

Wow! I got the bug now!
I had cast up some .44 310GC Lees in WW. My WW come out harder than most, as I have some old WW that I think have more antimony than the current stuff. They may also have some arsenic in them.
so I heat treated some @ 430F for an hour, yesterday morning.
32 hours later they are running 27BHN! They're really a good deal harder than I was hoping or needing them to be....
Now to send them downrange and see what might become of it. I've caught .44 heavies before, but it is a PITA, as they punch thru a lot of material....

Thanks to all for your input- I may be getting a small oven for the shop soon....

[onondaga]

If you heat treat again and allowed them to cool slowly by turning off the heat and keeping the oven closed until cold, that is as soft as they will get. Any kind of rapid cooling makes them harder. So, you can harmlessly bring the heat treated hardness back out if you wish.

Gary

[HighHook]

20 years ago my wife caught me in the kitchen heat treating my boolits and she threw me out and swore that I was poisoning her and family. I have got to get back in the kitchen to start heat treating again. Wish me luck...

[just.don]

found this somewhere, some months ago.

400 F 15
415 F 17
420 F 18
425 F 19
430 F 20
440 F 20
460 F 25
485 F 30

Cast bullets made from alloys including antimony and/or arsenic that are air cooled will continue to slowly harden for years.*
Bullets made from the same material that were quench cooled or oven heat treated will slowly soften for years.

hope this helps

[6bg6ga]

Quote:
20 years ago my wife caught me in the kitchen heat treating my boolits and she threw me out and swore that I was poisoning her and family. I have got to get back in the kitchen to start heat treating again. Wish me luck...

Sorry but I will have to side with her. Buy yourself your own piece of kitchen equipment to use instead of something she uses to prepare dinner.

[blackthorn]

Quote:
20 years ago my wife caught me in the kitchen heat treating my boolits and she threw me out and swore that I was poisoning her and family. I have got to get back in the kitchen to start heat treating again. Wish me luck...

6bg6ga replied: "Sorry but I will have to side with her. Buy yourself your own piece of kitchen equipment to use instead of something she uses to prepare dinner."

Sounds like a good excuse to re-wire the shop for a 220 stove! An added benifit would be having a place to cook your beans when you are not allowed in the house! Dr.Phil says past behaviour is the best indicator of future behaviour so---if she kicked you out once-------- LOL!!!

[HammerMTB]

Wow! I got the bug now!
I had cast up some .44 310GC Lees in WW. My WW come out harder than most, as I have some old WW that I think have more antimony than the current stuff. They may also have some arsenic in them.
so I heat treated some @ 430F for an hour, yesterday morning.
32 hours later they are running 27BHN! They're really a good deal harder than I was hoping or needing them to be....
Now to send them downrange and see what might become of it. I've caught .44 heavies before, but it is a PITA, as they punch thru a lot of material....

Thanks to all for your input- I may be getting a small oven for the shop soon....

Boy, I have no excuse-
Evidently I misread the 30X loupe by 10 thou, as testing these again finds them 20 BHN, not 27.
Which is convenient cause that's more like what I wanted, anyway. If they harden further, I don't expect it will be by much. The oven temp was pretty accurate, the results excellent.
Good excuse to go cast some more boolits! :cbpour:

[sqlbullet]

Cast bullets made from alloys including antimony and/or arsenic that are air cooled will continue to slowly harden for years.*
Bullets made from the same material that were quench cooled or oven heat treated will slowly soften for years.

Some testing I did last week to some 24 month old samples seems to indicate it is more complicated than this.

The summary is that bullets that were quenched, either from the mold or oven, to a BHN of over 24 softened.

However, ones that reached an initial BHN under 24, whether quenched or not, had hardened.

This leads me to beleive that there is a maximum 'stable' hardness a lead/antimony/tin allow can reach. If you exceed this hardness, your bullets will slowly soften back towards that number. If you don't reach it, they will slowly harden towards it.

Further supporting this is the fact that the greater the deviation either over or under, the more change in hardness that occurred.

I hope to get the complete data formatted and posted in the next few days.

[pls1911]

KUDOs to the good folks who study metallurgy more than they shoot... I used to do that, but haven't in later years, so I can't add much more than support to what's already been stated.
So, in the hope of helping someone press on to casting cheaply and conserving expensive resources, I'll relate my methodology.
I've oven heat treated for a long me and my barrels have been lead free forever...
I fully recommend the comment about cast soft alloys and heat treat as needed for applications... it's a great approach to conserving dwindling availability of WW and linotype.
And after toying with bordeline temperatures (465-475 ish) and getting half melted bullet batches for the headache, trust me.... just settle at 450 degrees for an hour, and save yourself the humor and grief of recasting a few hundred bullets.... Whatcha get will be hard enough!!

Having recently acquired a steady source for free roofing lead, (vent pipes, sheet flashing etc...), I've been pleased to find that ingots from this scrap measure 10-12 brynell, and show surface which cries out: "HEY!! There's tin in here!!"
So now I have about 800 pounds of promising ingots to go with the ton+ of old linotype, print blocks, babbit material, and wheel weights.

I've created a LOW antimony alloy at roughly 70-80% roofing scrap, and 20% my earlier "Lyman #2" mix. It casts nicely, is 12-13 brynell as cast and heat treats to 25 after one hour at 450 degrees and an ice water quench. So, "as cast" for pistols (.38s and .45s), heat treated with gas checks for rifles or magnum pistols... this alloy is a PIG POUNDER.

I use hardware cloth (1/4" squares) baskets fabricated as described in an RCBS cast bullet guide with coat hanger wire handles, abour 8"x8" in size. This allows 4 baskets with a single layer of bullets to be heat treated at once, and the weight is entirly manageable with welding gloves.

A 5 gallon bucket with 3 or four gallons of ICE water allows near instant quench from oven rack to ice water. All four baskets can be quickly stacked in a single quench bucket.... 1,2,3,4.... about that quick. It's a nice steam show for a wife who takes an interest in industrial arts practiced in the kitchen.
Of course the side benefit is that it's quick ... less time for considered discussion with wife...

The very economical result is rock hard bullets for full 30-30 or 45-70 performance, without the brittleness of higher antimony alloys. AND I've experienced no leading using Unique or Reloader 7.

[just.don]

The summary is that bullets that were quenched, either from the mold or oven, to a BHN of over 24 softened.

However, ones that reached an initial BHN under 24, whether quenched or not, had hardened.

This leads me to beleive that there is a maximum 'stable' hardness a lead/antimony/tin allow can reach. If you exceed this hardness, your bullets will slowly soften back towards that number. If you don't reach it, they will slowly harden towards it.

Further supporting this is the fact that the greater the deviation either over or under, the more change in hardness that occurred.

I hope to get the complete data formatted and posted in the next few days.


i know this is an old thread/post but i don't usually follow them for very long.
seems they often get "threaded" off into other points.
but i came back across this while searching for something else and it sounds like a good theory. alloys seek their natural bhn
just wondering if you ever got the time to get back to it.
i know around here time is in short supply



And after toying with bordeline temperatures (465-475 ish) and getting half melted bullet batches for the headache, trust me.... just settle at 450 degrees for an hour, and save yourself the humor and grief of recasting a few hundred bullets.... Whatcha get will be hard enough!!

concur....melted more than one tray myself