Heat treating, or how to ruin 100 boolits at once

[dubber123]

Tonight we (my brother and I), decided to venture into the magical world of oven heat treating. After reading all the wonderful things like batch to batch consistacy, convenience, etc. it sounded like a great idea. I was sure I had seen 425 to 450 degrees mentioned as the temp to bring the boolits to.

I decided to check before we got too far, so I did a search, and came up with the very handy LASC page, where they used clip on WW's at various temps to get varying degrees of hardness. 485 degrees was listed as giving 30 BHN after one hour in the oven.

First we checked the new toaster oven with a seperate thermometer. 425 was 425, 450 was 450, and max ended up as 470 degrees. We left it for almost a half hour after it hit 470, and it did not increase. Oh, well, not 485, but good enough. Put 100 boolits, (cast very carefully, and SLOWLY) out of a single cavity mould, ( probably 1-1/2 hours of casting) onto the tray, and into the oven. Drink a few beers, and 45 minutes later notice a couple boolits missing!. Several are melted over, almost all have a 3/4" foot on them now. All junk. 450 degrees does the same, 425 is stable.

This was a super fun experiment, I was wondering what the take was on a USABLE temp for heat treating. 485 degrees is obviously not it.

[stocker]

Most of the thermostats in common use operate within a range. You set them for 485 but the on/off range might be from 450 to 500 mostly caused by lag time in the thermostat responding to temperature changes. It may be worth your while to drink your beers sitting in front of the operating but empty oven except for a reliable oven thermometer in view and see if you can determine what range the thermostat operates within. Also, a toaster oven may be a bit crowded when the heating elements get red hot and the boolits are sucking in a whole lot of heat in a hurry. Perhaps a heat shield on a rack below your boolit tray might help.

[dubber123]

The heat shield idea is something to think on, it has heating elements above and below. We left the thermometer in the empty oven for at least a half hour, and it would not go above 470 degrees, 15 below what the LASC article said was fine for heat treating. I watched the elements cycle on and off several times during the test phase, and it still never went above 470. This is going to take some fiddling. Preferably with less than a whole evenings casting inside.

[runfiverun]

you need to remember that tin content will lower your melting point
like 2% will lower it to [just aguess off my head,about410]
more casting fun..

[Slowpoke]

guess you missed the part about trying a few cull boolits first. :)

Use your cull boolits as your thermometer, find the temp they melt at and then reduce heat 15 degree's and try again, and a again if need be until you are sure no melt.

In a toaster oven you will need a heat shield top and bottom plus a longer soak time, I generally go 2 hrs minimum. You can over do the heat shield just as easy as you can melt your boolits, it takes a little sperminting and note taking.

But as Felix says its all part of the fun.

good luck

[dubber123]

So far, 425 on the oven matches 425 on a seperate thermometer, and after an hour, we can see no boolits slumping. It would have indeed been nice to find this out without 100 of our best boolits in the oven. Live and learn I guess. Maybe it will all be worth it.

[waksupi]

425 is about my usual range before getting any slump. You should be good there.
Keep in mind, you can also use lower settings, to create different hardness. I did a chart using 25 degree increments.

[toecutter]

The thing you need to remember about toaster ovens is they are radiant heating... they don't use interchange of hot air to do the cooking. So while your thermometer may read one thing, it's entirely possible it's getting hotter than that based on the amount of absorbtion of heat lead is capable of (likely more than shiny stainless steel). A heat shield is exactly what you need. You could also immerse your bullets in something which will not melt and will not chemically react with them at those temperatures. While I can't think of the perfect product, one which does come to mind is talc powder (baby powder, but without the scent). Solid talc is used to mark metal which you are going to weld, and allows you to still have a visible mark when the metal is glowing yellow hot (about 1500F).

Let me know if this works. maybe one day I will make a bullet worthy of heat treating.

[Bret4207]

Try water quenching. Lots eaisier!

[44man]

I just water drop for convenience so I don't have to fool with moving hot boolits around on a towel. I never seen any difference in a boolit at 15 BN or one at 22 BN in how they shoot. I don't think it can be seen unless shooting BR.
But then, I am shooting revolvers, not rifles so most any boolit out of a group can be blamed on me and I know when I get a bad feel with a rest or a change in recoil from the rest.
The point is that I get good groups with a softer boolit or a harder boolit and don't see a POI shift bad enough to worry about.
I am a lazy, easy caster! :mrgreen: I will forever feel that a perfect boolit from the mold is more important then if it is 2 BN off from the last one. If I had to worry about that, I would buy boolits.
Dubber has sent me his boolits to try and I don't know why he is trying heat treating because his boolits are as perfect as any I have seen or made. He is at the top as far as being a good caster. :drinks:
I feel my friend is making himself more work just for fun. [smilie=1:

[theperfessor]

Has anyone tried using temperature marking crayons to check buller temp? You can get them in various heat ranges at any welding supply store. They're used by welders and heat treaters to check temperature for heat treating, annealing, pre- and post heating for welding, etc.

Just mark a couple bullets and when the stuff melts you've hit your mark.

Just a thought...

[bishopgrandpa]

I have to agree with 44MAN. I cast anywhere fron 14bhn to 17 bhn and see no need to harden them. I shoot mostly large bore pistol and rifle from 1200fps to 2400fps and do use gas checks. A good lube makes the difference many times. My loads have been used for the range and for hunting. No bullet has ever failed me. At one time when I had more linotype than I knew what to do with I made lots of (shiny) bullets for the 444 and 45-70. After going thru deer by way of their shoulders the bullets didn't shatter or in any way break up. Some posts extolling the fragile nature of Lino truly puzzles and amazes me. My experiences are not theoretical but practical in the woods use. I am 68 and have been casting for more than 40 years. Where have I gone wrong?

[stubert]

I have been casting bullets using a #2 lyman recipe. 9 lbs. ww and 1lb 50/50 solder. I shoot 44 spec. 44 mag. (full power with 296 and no gas check) I shoot 45-70, 35 rem. and 458 lott. all with the same alloy. I do not get leading and I am pleased with the accuracy. I agree about the lube. I use Lyman orange for everything. Only draw back is it needs to be heated to use.

[35remington]

bishopgrandpa, the claims for the fragile nature of linotype likely were gained from those users shooting them through rifles with higher velocity potential than your handguns and bigbore levers.

It's not a theoretical thing, as these users have seen lino shatter in practical use, too. Usually the bullet does not completely shatter but merely loses most or all of the front section. At least in my own practical experience.

On topic, my oven varies depending upon whether it's winter or summer in the time it takes to get up to temp and the time it needs for a good heat treatment. The surrounding walls act as insulation or a heat sink depending upon how cold/warm it is outside. I've found that by pushing it to the very limit 33 BHN is possible, but I don't like to run it that close to the edge. BHN 27-28 is more typical and adequate for most all of my usage. Incidentally, the dial reads just a squinch above 450. This for a mixture of wheelweights and a small amount of added tin.

Don't know what the actual temp is.

[454PB]

And, it doesn't matter what the temperature is....as long as it's a few degrees below the slump zone.

[dubber123]

Thanks for all the replies, the biggest reason is that I often cast a bunch of boolits, and before I use them all, a year may have passed, and the hardness is going away. I figured that we could cast them air cooled, and only heat treat a few days ahead of needing them, and in batches of 1-200. Water quenching has always worked well for me, but you need to size them right away, or you lose some of the surface hardness. A big hard boolit can be a bear to size also. (I broke my Lyman 450 twice doing this). Also, I just like fiddling with things, and this seemed like a good way to get a very consistant batch of boolits. I'm making lube and playing with the oven again tonight. I will have to look into the heat shield thing.

[cbrick]

dubber123,

Very interesting thread in that I wrote the article on the LASC site that you refer to. To start and as a SWAG I'd say the toaster oven could be the biggest prolem. How close to the heating elements were the bullets? Heat shields as suggested could help if there is room between the shields and heating element and shield and bullets, both top and bottom. 485 degrees should be under the melt point of WW alloy (barely) but as mentioned, test bullets should placed in the oven first to check for slump. Oven controls and thermometers do vary and not being laboratory grade equipment some are not even repeatable. The gas fired oven temp control I used wasn't repeatable and any time I tried for as hard as possible I had to test first for slump. I'd be very interested to know if anyone else has had a problem aproaching 485 degrees with WW alloy, if so I'll edit the article. I have never used a toaster oven and as the article says, when I started HT many years ago I used a gas fired full size conventional cook oven and then switched to an electric convection oven.

Your post didn't say what boolit you were using or for what cartridge but in all the testing of BHN I've done I haven't found a need for 30 BHN boolits. This is much too hard for most uses, even top end 454 loads.


I just water drop for convenience so I don't have to fool with moving hot boolits around on a towel. I never seen any difference in a boolit at 15 BN or one at 22 BN in how they shoot. I don't think it can be seen unless shooting BR.

Most HT is well served by simply water quenching and will get WW alloy to around 18 BHN. Most revolver shooting is something like 20 to 50 yards with open sights and most people are happy with 2 or 3 inch groups. 44man would be correct, it would be difficult to tell much difference in BHN under such conditions as long as bullet fit were correct and not either too hard or putty. The need for a specific BHN depends entirely on what your trying to acheive but even so, the testing (and article) indicated that a BHN range of 17-18 or 20-21 made little difference. A wider BHN spread, of say 15-21 made a big difference in groups. I haven't a clue what "moving hot bullets around on a towel" might mean.

The article was centered around accuracy testing I did with a 9" 357 FA scoped with a Burris 12X, grouped at 150 meters from the bench or, the BR shooting 44man mentioned. The alloy BHN did make a difference in groups, ES and average velocity.


I figured that we could cast them air cooled, and only heat treat a few days ahead of needing them, and in batches of 1-200. Water quenching has always worked well for me, but you need to size them right away, or you lose some of the surface hardness. A big hard boolit can be a bear to size also. (I broke my Lyman 450 twice doing this).

Exactly!

Rick

[mroliver77]

In my lead harvesting I come up with way more soft lead than WW or Lino. Heat treating allows me to use the least amount of valuable antimony for the same hardness.
In the .30 cal 311440 boolit out of water dropped WW my boolits were shattering in a box filled with wet newsprint at around 2300 fps. I backed off on speed until boolit performed as I wanted and erred on the safe side. In checking wound channel in a couple downed deer the boolit performed as in the test media and made a complete pass through with a 1"+ wound channel. IF I would not have done this I believe boolit would have shattered and not done near the damage and possibly lost the deer. A boolit with less antimony heat treated hard enough to withstand my load the boolit is less prone to shattering and can be driven faster for less drop and greater "point blank" range. Jay

[cbrick]

I almost agree with bishopgrandpa, i think the word "shatter" is to strong of a word in general shooting with lino. To many people use lino to think otherwise. I have seen lino rifle bullets that had the nose broken off but not all that often. Lino is getting more difficult to find and more expensive and there are alternatives such as HT that will give the desired alloy strength without the brittleness of a 12% antimony alloy. HT WW alloy can easily match the BHN of lino and is more malleable at the same time. In a hunting bullet (even a WFN) that can't be a bad thing.

Where the word "shatter" does apply with lino is shooting steel targets. On steel it does shatter and in dramatic fashion. Don't ask how many matches I lost trying to figure that out.

Rick

[w30wcf]

dubber123,
Sorry to hear that you lost a few hours of bullet making.:(

I have been heat treating some of the bullets I shoot since the early1980's. I originally started doing it to maximize the weight of a 311620 by using w.w. for the purpose of shooting the 500 meter steel ram silhouette. More weight = more momentum.

I use a toaster oven with a hole drilled through the top in which I insert a Lyman thermometer. I place 100 or so .30 caliber bullets into a round steel strainer basket. I set the strainer on two 1/2" diameter steel rods to insulate the base of the strainer from the bottom pan. The strainer is positioned under the hole and the Lyman lead thermometer lowered into the strainer.

I have found that my oven cycles of and on from 440F - 455F. I have found that temperature range to work the best for my application.

I use the same toaster oven to preheat my bullet mold(s) before beginning a casting session.:-D

Good luck,
w30wcf

[Bass Ackward]

The term .... lino is what makes apples to apples impact comparrisons deceptive. You can have fresh lino at 12% antimony with 6% tin. Or you can have 12 antimony with almost no tin as it was lost during use before you got it. Both are called lino.

Which of those do you think would be more brittle upon impact? So actually the problem is with our belief that what we are comparing is truly lino. Sometimes it is, sometimes it ain't.

Bullet diameter and impcat velocity are the other big issues.

[grumpy one]

The only lead-antimony-tin alloy that will melt at 485* is pure linotype, which melts at 462*F. Your oven temperature was more than 550*F if it melted wheelweights.

The last graduation on some ovens is actually just "constantly on", without thermostatic control. Probably yours is one of those. Another point to watch is that mechanical thermostats have a dead band, between switch-off and switch-on, which amounts to 25*F on mine, so you need to observe for a while before you feel too convinced that you know what temperature you've set the oven for.

As a practical matter you need to leave the thermometer in the oven throughout your heat treatment process, and actually keep an eye on it until you've done so many batches successfully that you can be pretty sure you understand your oven, and your thermometer. At the moment it sounds as if your thermometer might be in need of checking.

[44man]

Cbrick, what I meant was that I have only a small space on my bench between the grinder and drill press to dump boolits on a towel. I have to move them back out of the way often to make room for more fresh boolits. I usually pick up the edge of the towel and roll them back a little. Then I have to start putting the cooler ones in a box as I cast.
It is nicer to just drop the boolits in a bucket of water on a stool.
Merely a space limitation. :Fire:

[cbrick]

Ah, that makes sense, I couldn't figure out how a towel got into the conversation :-D.

[dubber123]

Success, I think. We initially tried the "toast" function, as it heats above, and below, and the temp seemed to stay at 470 via a seperate thermometer. This is what killed the first batch off. Tonight we tried "broil" which heats only from above, and while it didn't melt any boolits, we couldn't keep the temp within 90 degrees, going from 410, to 500. No good.

Tried "bake" next, boolits melted on the left side of the tray by the time the thermometer said 425. The whole time we were trying upper and lower shelves, btw. Realizing as suggested we needed a heat shield, my brother noticed a "crumb tray" came with the new oven. Placing this over the lower heating element, and using the top rack, we hit 435 on the thermometer, and it never moved, very consistant. 100 boolits on the tray for 1 hour 5 minutes, and no slumping at all, and they mic exactly as they started.

We were too chicken to increase the temp. Tomorrow I will try it with some culls at a higher temp. It is likely the higher temps can be reached with the ovens heat evened out. Even though in our first test, the thermometer said 470 degrees, there was likely some hot spots well over that #, causing our problems. 2 of the decent ones from that first disaster tested at 29 BHN today. If the ones quenched at 435 hit 25 BHN, we likely won't go any harder. Thanks for all your help.

[cbrick]

dubber,

Good news figuring out the toaster oven.

Just out of curiosity, what cartridge & action type are you heat treating these bullets for & at what velocity? Also for no better reason than curiosity what BHN tester are you using? Curious minds would like to know, thanks.

Rick

[Naphtali]

Regarding toaster-ovens, is there any testing whose results identify those ovens with more precise temperature identification, with more uniform (over time of soak) temperature control?

Is there a step upward in terms of commercial ovens, in control and uniformity, that does not break the bank account?

I had a toaster-oven several years ago. I was impressed with its lack of control and uniformity. Hot spots that were not hot spots all the time.

[cbrick]

Regarding toaster-ovens, is there any testing whose results identify those ovens with more precise temperature identification, with more uniform (over time of soak) temperature control?

Is there a step upward in terms of commercial ovens, in control and uniformity, that does not break the bank account?

Naphtali,

Breaking the bank would be different for everyone and would depend on your bank account, how much of this you do and how important the convenience and accuracy is to you. I used a gas fired conventional oven for years and it was a pain in the heiny. Its temp control was way off and not repeatable two times in a row. It took an hour to a an hour and a half to get the temp correct every time I tried to HT. It also didn't hold a constant temp and once bullets were in it I had to watch the thermometer constantly. When the temp started to rise I opened the door a bit to allow heat to escape. It did work though and I did many thousands of bullets this way.

I was in a store a few years ago and there on the shelf was a shiny electric convection oven. It was big enough to hold stacked trays of bullets. The paper work with it said that it held a constant temp at any of its settings. With sales tax [smilie=b: it was nearly $450.00. Yikes. More than I should be spending at the time but all I could think about was the hassle of the gas oven so I bought it. Turned out to be the best decision I've made in a long time.

Now I simply set the desired temp, wait 10 minutes to pre-heat, set the timer for 1 hour and put the trays of bullets in. The temp doesn't vary more than a couple of degrees and at the end of the hour a bells sounds and I slide the trays out and into the water. Done.

http://www.lasc.us/DSCN0169-2.jpg http://www.lasc.us/DSCN0230-2.jpg

I made the trays from heavy gauge flat bottom spaghetti pans with the side holes enlarged for better water flow. Each tray holds 300 35 cal bullets so in one session I'm good to go for some time.

I do very little annealing but when I do its a simple matter to set the temp, timer and put the bullets in, done. The timer shuts the oven off and I come back the next day to room temp annealed bullets.

Rick

[dubber123]

dubber,

Good news figuring out the toaster oven.

Just out of curiosity, what cartridge & action type are you heat treating these bullets for & at what velocity? Also for no better reason than curiosity what BHN tester are you using? Curious minds would like to know, thanks.

Rick

Rick, initially we are experimenting for the .475 Linebaugh. Looking at getting a 440 grain plain base boolit to 1,325+ out of a 4-3/4" F/A. or a 6-1/2" BFR. This velocity is attainable with a GC design with great accuracy. My brother has shot air cooled 410 gr. plain base WW's to 1,360 fps. with minimal leading, but no serious accuracy testing yet. We are using an LBT tester, and trying each batch several times to get an average. We just bumped the temp to 450 degrees, without slump. Any thing over that was causing melting. At 465 degrees, per the seperate thermometer, the bases of some grew 10 thousandths, so they were definately on the way out. Your (much) higher quality oven is likely responsible for being able to attain the higher temps. If we can get a consistant 25 bhn, we will be happy. With the heat shield, we can keep temps within 5 degrees or so. I will keep you posted. Thanks.

[grumpy one]

dubber, any reasonably commonplace lead-tin-antimony alloy that is not a eutectic will have two phases when melting or solidifying. For just about all the ones commonly used for bullets, one phase will consist of pure linotype. That is, as you heat the alloy, when you get to 462*F one phase will melt and the remainder will remain solid until you reach some higher temperature. For WW that higher temperature where the second phase will become completely molten will be around 550*F or so.

What this means is that you aren't likely to melt your bullets too easily, but as soon as they exceed 462*F they will slump. How much they slump depends on how much alloy is in the first melting phase - and that depends on how much tin and antimony your alloy contains. Pure WW has very little tin and not a whole lot of antimony, so it won't slump enough to observe visually until you get up above 475*F. However an alloy like electrotype (2% tin, 6% antimony) is likely to slump pretty awfully at 475*F. So in the end, low tin alloys are quite a bit more forgiving of temperature excursions in the HT oven. Regardless of all this, you won't actually melt bullets into puddles unless they get way up around 550*F, unless they are pure linotype.

This thread started off with a report of low-alloy bullets melting completely in the HT process, and that means they must have reached around 550*F.

[cbrick]

Your (much) higher quality oven is likely responsible for being able to attain the higher temps. If we can get a consistant 25 bhn, we will be happy. With the heat shield, we can keep temps within 5 degrees or so. I will keep you posted. Thanks.

This oven is of a higher quality than most any toaster oven I've seen but the thing that makes it far better as an oven is the convection heating. The bullets are well away from the heat source behind a shield, a fan circulates the hot air throughout the entire oven. A very uniform, even heat with no hot or cool spots anywhere in the oven.

Rick

[dubber123]

dubber, any reasonably commonplace lead-tin-antimony alloy that is not a eutectic will have two phases when melting or solidifying. For just about all the ones commonly used for bullets, one phase will consist of pure linotype. That is, as you heat the alloy, when you get to 462*F one phase will melt and the remainder will remain solid until you reach some higher temperature. For WW that higher temperature where the second phase will become completely molten will be around 550*F or so.

What this means is that you aren't likely to melt your bullets too easily, but as soon as they exceed 462*F they will slump. How much they slump depends on how much alloy is in the first melting phase - and that depends on how much tin and antimony your alloy contains. Pure WW has very little tin and not a whole lot of antimony, so it won't slump enough to observe visually until you get up above 475*F. However an alloy like electrotype (2% tin, 6% antimony) is likely to slump pretty awfully at 475*F. So in the end, low tin alloys are quite a bit more forgiving of temperature excursions in the HT oven. Regardless of all this, you won't actually melt bullets into puddles unless they get way up around 550*F, unless they are pure linotype.

This thread started off with a report of low-alloy bullets melting completely in the HT process, and that means they must have reached around 550*F.



If my first post was misleading, I apologize, none of the boolits were complete puddles. Probably 75% had a large "foot" and 2 of them melted enough to tip over, and had a puddle going along their sides. This was with heat above and below, and the seperate thermometer reading 470 degrees. There were some obvious hot spots going on, as we had nothing for a heat shield, and they were on the bottom rack. With a shield, and on the top rack, they went well over 1 hour at 450 with no problems. At 470 degrees, even on the top rack, I could see "spots" forming on one of the two test boolits, and it had grown 10 thousandths when cooled and measured.

[dubber123]

Tested 3 samples of the batch quenched at 450 degrees. Within about 20 minutes, BHN was up to 18, from an air cooled 14-15, and today at 24 hours, 3 samples tested at 25 BHN. Will re-test again tomorrow to see if they have leveled out.

[dubber123]

At 450 degrees, the boolits reach 29 in about 2 days. After all this, during speaking with cbrick here on the forum, it appears there is such a thing as too hard, even with the very high pressures I'm testing at. I always assumed this gun, a .475 that operates in the 50,000 psi range, needed all the hardness it could get. As a test last weekend, I tried some air cooled, (14 BHN) boolits at full throttle, which is a 440 gr. boolit at 1,325 fps from a 4-3/4" barrel. I truly expected a barrel full of lead, but much to my surprise, there was less leading than with the harder slugs! I'm not well tuned up for group shooting with a handgun, but the 3 groups I tried were close to what I expect from this gun. I will have to test some more, maybe there is a magic BHN number for this gun. Another good thing about heat treating, I can dial in a desired hardness.

[cbrick]

dubber, consider your results with the 475 and pressures in the area of 50,000 psi and you'll understand why I cringe when I hear the term "hard cast". Hard cast is not needed in many instances and can be detrimental to accuracy and leading. Most commercial cast bullets are in the 20-24 BHN range and a lot of handgun loads are well under 30,000 psi.

Heat treating can be a valuable tool for a bullet caster but too much of a good thing is not a good thing. Now that you know what's too hard for your load in your gun its very possible that you'll find a BHN of 16-17 or maybe it'll be 19-20 where there is less deformation of the alloy and yet its not too hard. Testing, testing, testing :-D, good thing its fun, at least for me. Besides, look at all the additional range time you can get.

Max hardness of your HT bullets in 2 days indicates that the antimony content in your WW is up around 4%. In HT tests I did with lower Sb I got the same HT BHN but it took much longer to reach the final BHN, almost three weeks in one such test.

Rick

[Ricochet]

I found a little blurb in the Metals Handbook to the effect that 1% antimonial lead took a long time to reach equilibrium hardness, perhaps a year or more. I've seen some on here state firmly that less than 2% antimony could not be quench hardened. I know from experience that very soft scrap lead (of unknown composition, but obviously much softer than 2% antimony) that I can easily dig my thumbnail into will harden substantially after quenching; it just takes a while. You have to be patient.

[cbrick]

Ricochet,

That's been my experience, once Sb is under around 4% the longer it takes to reach its final hardness and the more under 4% the longer it takes. According to all of the metals industry reports I've read this holds true in industry as well. Perhaps those that state flat out that it doesn't work simply didn't wait long enough. Industry recommends 6% Sb as optimum for the hardening/time curve but to my way of thinking 3%-4% and 2-3 days is just fine for bullet casting. Most WW alloy should run in the 3-4% Sb range.

Rick

[dubber123]

Rick, in another gun the testing would be more fun. Shot # 4 took a .304" chunk out of my top thumb knuckle. (Yes I used a caliper to measure it). I may don the sissy glove till the callouses thicken up again.

[Bass Ackward]

I always assumed this gun, a .475 that operates in the 50,000 psi range, needed all the hardness it could get. As a test last weekend, I tried some air cooled, (14 BHN) boolits at full throttle, which is a 440 gr. boolit at 1,325 fps from a 4-3/4" barrel.


:grin: Two different techniques.

Hard and match the pressure to the hardness before the bullet deforms.

Shoot a softer bullet and let it deform evenly.

I shoot allot the softer way at HV. Just depends on how everything comes together.

[Bass Ackward]

I found a little blurb in the Metals Handbook to the effect that 1% antimonial lead took a long time to reach equilibrium hardness, perhaps a year or more. I've seen some on here state firmly that less than 2% antimony could not be quench hardened. I know from experience that very soft scrap lead (of unknown composition, but obviously much softer than 2% antimony) that I can easily dig my thumbnail into will harden substantially after quenching; it just takes a while. You have to be patient.


Patient? As in waiting for a repeat of your WBY testing? :grin: Did you sell that by now?


Wait a year for bullets? I don't think so. :grin:

[Ricochet]

I do need to get back out with Mr. Weatherby. Those boolits have been aging for a year and a half or so, I think. :mrgreen:

[dubber123]

:grin: Two different techniques.

Hard and match the pressure to the hardness before the bullet deforms.

Shoot a softer bullet and let it deform evenly.

I shoot allot the softer way at HV. Just depends on how everything comes together.

So even though the hard boolits I was shooting were well fitted to the throats, they could still be lead prone by virtue of being too hard? Thats certainly how it appears, the softer boolits leaded less, even at the very high pressures. I would guess as cbrick has stated to me, there is a magic bhn number for all gun/load combos. Mine will apparently fall between 14 and 29[smilie=1:. Thats alot of testing, but it will have to be done, if I want optimum results.

[cbrick]

I would guess as cbrick has stated to me, there is a magic bhn number for all gun/load combos. Mine will apparently fall between 14 and 29 [smilie=1:. Thats alot of testing, but it will have to be done, if I want optimum results.

I don't think I used the word "Magic" though. :-D Nothing magic about it, testing & fine tuning, an educational process to learn how, why & what's possible to make it the best you can with your own two hands & then know both why and how to do it with the next one, and the next one. Hopefully with a tad longer barrel. :(

Rick

[Marlin Junky]

450F in a convection oven will not damage clip-on WW metal and one hour at this temp will raise the BHN from 11-12 to 20-21 after curring for about a week.

MJ

[dubber123]

I don't think I used the word "Magic" though. :-D Nothing magic about it, testing & fine tuning, an educational process to learn how, why & what's possible to make it the best you can with your own two hands & then know both why and how to do it with the next one, and the next one. Hopefully with a tad longer barrel. :(

Rick

No, I don't think you used the word "magic" either, call it a "literary embellishment"[smilie=1: The optimum bhn would have been a better way to word it. I freely admit the longer tubes are easier to work with, but the shorter ones carry soooo nice! A 4-3/4" .475 would be a pretty dumb choice for a dedicated bench gun. I threw the homemade lube variable in too, which isn't the right way to do things either. One change at a time.

[dubber123]

450F in a convection oven will not damage clip-on WW metal and one hour at this temp will raise the BHN from 11-12 to 20-21 after curring for about a week.

MJ

Mj, whatever we are doing, we are getting 29 out of these boolits in as little as 3 days. (LBT tester, 3 sample average). They are BIG handgun boolits, 440 grains, maybe that makes a difference. We are quick from the oven to the water too. The 450 degrees on the oven dial matches 450 on a seperate thermometer. This seems too hard anyways, so I will shoot for 18-20 next.

[Marlin Junky]

What are you placing the boolits on? I use a wire basket (stationery section of Wally World) on the center rack of the kitchen oven (set for convection bake) and plop the whole thing in ice water as quickly as possible. My thermometer is hanging just above the boolits and reads just under 450F while the thermostat of the digital oven is set at 450F. To get your boolits that hard in only 3 days, I suspect they are over 450F when quenched.

MJ

[cbrick]

MJ, dubber's results are fairly close to my testing given even minor variation in alloy, ovens, thermometers etc. I get very close to max hardness in 3 days with an alloy in the range of 3-4% antimony. In fact, 3 days is the standard that I judge by. The only tests I've done that took longer was with alloy with less than 3% antimony.

The antimony percentage is what effects the age hardening/time curve. If your heat treated WW alloy is taking longer its probably because of a low antimony percentage. Metals industry reports I've read suggest antimony at 6% for an efficient age hardening/time curve but for bullet casting with WW and antimony of 3-4%, 3 days is good. In industry time is money and 3 days is not good.

Another thing that effects the final outcome is the type of BHN tester used, they vary more than the ovens, thermometers and alloy combined.

Rick

[Bass Ackward]

So even though the hard boolits I was shooting were well fitted to the throats, they could still be lead prone by virtue of being too hard? Thats certainly how it appears, the softer boolits leaded less, even at the very high pressures. I would guess as cbrick has stated to me, there is a magic bhn number for all gun/load combos. Mine will apparently fall between 14 and 29[smilie=1:. Thats alot of testing, but it will have to be done, if I want optimum results.


See everything is a balance that you haven't found yet. Or maybe you have.

You have to correctly interpret WHAT kind of leading you are getting. Instead of a hardness issue, this could be a sizing issue. I have seen .0005 clean this all up. Or size the bullet deeper into the die type of thing.

Or it could strictly be a gun or lube issue that will clean up over time. But no matter what I use, the "trend" I see is: the harder and faster I want to go, the closer to groove diameter I want to be.

[dubber123]

I'll try and answer both Bass and MJ in one post. MJ, ours are placed on the metal tray that came with the oven, they have to be on the top rack, with a heat shield directly over the lower heating elements. The seperate brass thermometer sits right in the tray with the boolits, and seems stable within 5 degrees. At about 465 degrees per this thermometer, the boolits start to slump. Bass, the leading is minor, with all lands and grooves remaining sharp, it just has gray streaks in the bore, that were noticeably lighter with the softer boolits. The cylinder throats measure .4760" on all 5. (Nice). Boolits have been sized from .47625" which is as big as will chamber, (very tight chambers), to .4760" which is my current set-up. I tried .474" once, and got alot of fouling, and a big velocity drop. The high 29bhn #'s are likely as cbrick stated, just a variance in testers. It is a good tester, an LBT, but all calibrated tools can be off.