What Causes Boolit Shrinkage

[AriM]

When faced with something that seems inexplicable with things I have been taught, I turn to simple logic for a possible answer.

When I drop a Stanley 16 ounce hammer on my toe, it hurts. Every American-made 16 ounce hammer I have dropped causes the same amount of pain.
But, I have two Chinese hammers that are marked 16 ounce. Both of them make my toe hurt more.
Logic would lead me to believe the Chinese hammers weigh more than their markings indicate.

A mould maker knows a bullet alloy will shrink upon cooling. So, he knows the cavity he cuts must be larger (by some predictable amount) than the bullet the customer wants to cast.

The maker also knows that different alloys shrink varying amounts, so he usually has a list, or chart, or some other means of choosing the size he will make the cavity. Perhaps the chart was developed using pure math...maybe it came about through personal experimentation...or he might have obtained the data from the Chinese.

In any case, his moulds (and only his moulds) 'exhibit the same behavior', one that does not please you.
Is it possible that his cavities are cut to the wrong dimensions...perhaps because his chart is wrong?

If eliminating the logical still leaves a question, then it may be worth the trouble of an in-depth study of the metallurgly and chemistry involved.

Or not...

CM

first off let me say.....your post is hilarious and made me smile. so all things aside, it's a great response.

I would question the mould maker and the design, except for this one fact. He claims that other customers are dropping at 453, and that I should also be dropping at 453. I have tried most of the logical variations (I can think of myself). I have tried the suggestions of others. I have tried the suggestions of the maker. The results are un-satisfactory. Out of all of the other moulds I own in this size (approximate size) this is the onlly one that is giving me trouble. So I am considering that there is something going on, that I can't account for. I like to try and take responsibility before I point the finger.....it saves me from looking like an ******.....or maybe not

[AriM]

I can prove this wrong, and I've done the testing. Heat treatment hardens more than the surface.

I've never used a brass mould, but I recall the new learning curve when Lee began making aluminum moulds. For years before that, I had used nothing but steel moulds. My casting technique had to be changed to produce acceptable boolits. I assume the first use of a brass mould would be the same.

can you please post the proof? or at least the data, as I would have to disagree with this. not based on one guy being right or wrong, but just based on my own experiences.


also do you mean steel moulds? or iron?

I do have experience with aluminum moulds.....and I now have at least half a dozen tries with brass.....

I am still assuming the problem is me, and not the mould....i want to be respectful and fair to the mould maker....I believe what he has done for us is wonderful and I appreciate him and his willingness to stand behind his product, very much!!!



P.S. is that a fender bass or a lakeland? i also play....

[AriM]

I didn't me mock in a sense of ridicule..........a ment a mockup

I will definately make that change............see..............I told you a simple slip in vocabulary usage and we have a totally different intent

touche'!!!!!!

I think this is where the obturation thread went wrong. I have made lengthy and numerous posts in that thread, as have others. I finally came to the conclusion that it was a debate over semantics. When the theories were approached with more detailed observation and didn't rely on blanket statements or one word definitions, I quickly discovered we were all on the same page.

Thank the tower of babel for all of this muck....i say tomato you say tomatto....I say potatoe you say airplane....

[AriM]

Keeping up a fast, consistent casting pace is the best method I have found for when the mold needs to be kept hot, but the alloy not overheated. Do not pause during casting to do quality-control, fiddle with gear, restock ingots, etc.



Now, I too have noticed what appear to be intermetallic crystals in the melt, as I do not often cast at higher temps. While this may not seem like a satisfying answer, I pay those crystals no mind. Their presence apparently does not affect the quality of my castings in any negative way. I also do not often pour alloy that has more than about 10-12% Sb, but on occasion I get a batch of monotype that appears to have more Sb than that. I blend it back down to about 12% Sb max. Fluxing seems to help decrease the amount of intermetallics. Flux early, flux often.

ok before I give my praise and thanks, i have to point out the items I made red. this is my biggest problem. i flux early and I flux often.....this seems to slow down my casting though.....ok ok ok....idea....i am going to run 2 separate pots....one to pre melt and flux in and one to cast from.....that should keep the fiddling to a minimum....also i will be sure to put the mould on a hot plate between pours....excellent dialogue

I have noticed, as you have, that the large crystaline structures can be fluxed back into the pot, quite easily.....I suppose one can't flux too much....or at least flux, with the intent of blending alloy....I suppose fluxing with the intent of skimming dross, would be bad....or at least we would be throwing out a lot of good alloy

I think I am going to do the 2 pot thing...the more I think about it, the more it makes sense....i can use a ladle pot (no bottom spout) to pre-melt and flux....then i could cast from a bottom pour. I could run some sawdust/kitty litter on the top of the bottom pour pot, to keep oxidation to a minimum. this way i can worry less about fluxing and more about keeping my mould hot. seems to make sense, at least it does in my cluttered little head....

here is the funny part....my cheap ass lee aluminum 6 bangers, require none of this attention....I get em hot.I get the melt hot....I ladle cast.....they look like **** (frosty as hell) and shoot PERFECT!!!

accurate, no leading, easy to lube, easy to make....easily handle MAJOR loads......100% feeding reliability

the lee 230-rn2r-tl is hands down the best mould and best boolit I have ever cast/shot.....maybe I should just give up on trying to find something better....hell what I have already out shoots me

then again, I seem to be having more fun casting and developing loads, and building guns....somehow I find myself shooting less and less....

[RobS]

AriM:

Here is a great link to a man who designs molds for a living. Take note to his suggestions to high temps and brass molds. He breaks down his thoughts on mold material, bullet weight, and alloy used. I for one have had many molds made by him and they are always spot on or .0005 ish over.

Possibly some insight to what you are working through:

http://www.mountainmolds.com/phpBB3/...c.php?f=5&t=60

[Bullshop]

Q: "What Causes Boolit Shrinkage"
A: "Obturation"

[AriM]

AriM:

Here is a great link to a man who designs molds for a living. Take note to his suggestions to high temps and brass molds. He breaks down his thoughts on mold material, bullet weight, and alloy used. I for one have had many molds made by him and they are always spot on or .0005 ish over.

Possibly some insight to what you are working through:

http://www.mountainmolds.com/phpBB3/...c.php?f=5&t=60

excellent, read the whole thing....helps to put a few more pieces in the puzzle....brass seems to be fickle....

i think, in the future, i am going to stick to aluminum....

I have brass, i have iron, and I have aluminum.....

the iron likes to heat up way too fast....it drops very sharp boolits....but the weights are all over the place

so far brass seems to drop undersized and has issues filling out with pure Pb....

aluminum seems to digest everything thrown at it....weights are consistent....sizes are good enough to uniform in a sizer....and I just run the pot wide open and the mould will cast all day w/o overheating....

best combo for subsonic pistol loads?

aluminum mould and an alloy equaling 9-11 BHN....this seems to be perfect for a pressure range between 11000 psi and 13000 psi

of course I am over simplifying it....but that is the basis of my point....the Lee 6 banger seems to make it simple....every day I gain more and more respect for Mr. Richard Lee

[Red River Rick]

I wanted to change my alloy so it wouldn't shrink as much, giving me a larger diameter bullet.

So I added some Viagara to the mix. The OD stayed the same, no change, but they became "Armour Piercing", due to the extreme "HARDNESS". I saved a lot of Antimony this way.

RRR

[AriM]

Q: "What Causes Boolit Shrinkage"
A: "Obturation"

smartass

[AriM]

I wanted to change my alloy so it wouldn't shrink as much, giving me a larger diameter bullet.

So I added some Viagara to the mix. The OD stayed the same, no change, but they became "Armour Piercing", due to the extreme "HARDNESS". I saved a lot of Antimony this way.

RRR

did your medical insurance cover that?? and if so, does your ep. know what you are doing with those pills? you know the pillmaker charges your insurance company something like $18 for each one of those


add's new meaning to the term "pocket-rocket"

[AriM]

This is not correct. Independent testers have found that the hardness is essentially unform from the edge to the center.

You're might think I'm being picky, but it is the one who proposes the theory who is required to prove it. One cannot rationally pose a theory and then ask others to find the evidence that disproves it, so no one here is obligated to provide evidence for their opposition to your theory of quench hardnening. That's the way science works.

However, one can intuitively grasp that the hardening effect is not a surface treatment, as the hardening happens over a period of time, and is not instantaneous upon quenching. It's a physical change within the entire crystal structure itself, and not a surface change.

On a practical level, the lead castings in a bullet mold cool too rapidly to allow much segregation of alloy component by distance from the edge of the casting, and far too rapidly to allow migration of alloy components. One can observe this with a hand-lens on the base of a bullet cast of ww alloy.

Not trying to nitpick, just tossing that into the pot!

question then....

why when you do a brinell hardness test, is it suggested that you make sure not to file too deep of a flat on the test sample. it clearly states in most instructions (that come with the test devices) that the material under the surface will be softer than the surface....and could cause an erroneous reading....

I can verify, that if I test a sample, with a Lee hardness tester....the more i dig into the casting...the softer the reading.....is some other factor coming into play?

it is the suggestion of the test equipment that the outer shell will be harder....also i have seen this written in many different places....perhaps a test is in order?

if anything to prove that i am mistaken....would you accept the results of a documented test on this matter? or are you 100% sure that you are correct?

P.S. are you suggesting that i have asked someone else to prove my own theory? I did dispute the gentleman who said he has proof of the opposite of my theory....he claimed he could prove it.....also in the same post he said that he had to get used to aluminum mould, after years of using STEEL moulds....I am not aware of anyone who makes a steel mould....but I assumed that I had just never heard of a steel mould....this is why i asked him....


P.S.S if alloy can oxidize in a pot....why can't it oxidize in a mould? isn't this partially what causes frosting over of boolits? the boolits aren't frosty inside....that would mean that something on the surface is different than something under the surface....not trying to quibble, but I would like to know

P.S.S.S i know this is off topic, but I have another theory about why frosting takes place....maybe i should start a new thread.....geeez by the time i get done with all my whacky theories...I'm not gonna have many friends on here.....oh well.....a wise man once said....i am what I am.....actually Popeye also said that

[AriM]

I also seem to remember reading, that one should never test hardness on the base of a boolit....because it is softer than the shank

[AriM]

Please read this excerpt....and also please follow the link and read the article....this article is linked from the Lee precision website....

Lee suggests this article as further information on their product....I hardly think Lee would link something that they felt was incorrect....and it is also inline with Richard Lee's writings about heat treating...


" Instructions for the tester indicate a flat is to be filed on the side of the test bullet for a contact surface. The initial bullet I tested was a Cast Performance item advertised as heat treated to a BHN 16~21. I wasn't sure how deep the heat treating went, and I didn't want to remove too much material and get an erroneous reading. For reference, wheel weight alloy has a BHN of 9, linotype has a hardness of BHN 22, pure lead is BHN 5.

Heat treating is an easy way to get to a surface hard cast from a softer alloy recipe. The radius of the .458" bullet is large so there is plenty of surface for the indenter ball to make contact, however, I did take two measurements; one without the flat and one with, so I could compare the two and see if filing away the surface made for a different BHN result. The flat cut was approximately .008" deep and the readings were the same. Lee cautions to never check hardness at the base of a bullet as this surface is frequently significantly softer than the sides or nose. The base is typically used to the support the bullet in process, such as hardening, and may not be subjected to the same temperatures and treatment."


here is a link to the Lee Precision page, and also a link to the article that is referenced on the Lee precision page, for their hardness tester
http://leeprecision.com/cgi/catalog/...l#LeadHardness

http://www.realguns.com/archives/118.htm

please read the articles and the lee precision page....if the excerpt above is not enough

now the article clearly states that the flat cut did have the same reading....so i am not sure what you will take from this

but it has been my previous experience that a flat cut too deep will encounter a softer reading

i can't verify if this is because of some other factor

I have a brand new in the box tester arriving on monday/tuesday....the reason for a second tester, is that i want to verify the one I currently have....

if I was willing to test a series of boolits....using a brand new, factory calibrated hardness tester....and was able to show that the core of a heat treated boolit is in fact softer than the surface....would you accept these results?

According to the tests of hardness testers on the LASC pages (i will find the article if necessary) the Lee hardness tester provided the closest BHN, in comparison to the laboratory test. the cabine tree had the smallest deviation, but the lee was still the closest to the actual BHN....

also I am not sure the actual BHN is important....we are only trying to show that the surface is harder than the core.....or that the entire boolit is an equal hardness...from surface to core

if you would like to help determine some parameters for this test...i am willing to include them....

this is not an issue of right or wrong....it's an issue of coming to some kind of verified conclusion....after all, in truth, everyone wins...

[RobS]

My results have been similar to AriM regarding the water quenching or heat treating of larger bullets. My results show me that as I oven heat treat bullets, the hotter they become the further in the hardness goes. This is more so with larger bullets i.e. my 454 Casull bullets for me anyway.

I will also note that my rifle bullets that are thinner as the caliber is smaller actually will be the same hardness through and through or at least very close in hardness if I heat treat them to the point where they almost melt.

Here is another good one for the what if's since we are now off thread topic. As most metals work harden, it is common knowledge that lead work softens. So what about water quenched or oven treated bullets that are sized after heat treating? What happens to those drive bands? Well of course they become softer if sized and I've tested the bands..........without filing them (which is very, very difficult to do by the way). I've found that if a person wants the bands to be as hard as the rest of the heat treated bullet you have to either size the bullets before heat treating or...................................directly after casting the bullets (I do them about 30 minutes after casting) size them and your bands will be only about 1 bhn or less from the rest of the bullet. These are my experiences and each person may have varying results of course.

AriM: Food for thought and by the way.....................you'll have friends here as we are all capable of putting our egos aside to listen to one another and then in the end understand that we can agree to disagree sometimes.

[AriM]

My results have been similar to AriM regarding the water quenching or heat treating of larger bullets. My results show me that as I oven heat treat bullets, the hotter they become the further in the hardness goes. This is more so with larger bullets i.e. my 454 Casull bullets for me anyway.

I will also note that my rifle bullets that are thinner as the caliber is smaller actually will be the same hardness through and through or at least very close in hardness if I heat treat them to the point where they almost melt.

Here is another good one for the what if's since we are now off thread topic. As most metals work harden, it is common knowledge that lead work softens. So what about water quenched or oven treated bullets that are sized after heat treating? What happens to those drive bands? Well of course they become softer if sized and I've tested the bands..........without filing them (which is very, very difficult to do by the way). I've found that if a person wants the bands to be as hard as the rest of the heat treated bullet you have to either size the bullets before heat treating or...................................directly after casting the bullets (I do them about 30 minutes after casting) size them and your bands will be only about 1 bhn or less from the rest of the bullet. These are my experiences and each person may have varying results of course.

AriM: Food for thought and by the way.....................you'll have friends here as we are all capable of putting our egos aside to listen to one another and then in the end understand that we can agree to disagree sometimes.

my tests show almost identical results. ESPECIALLY the issue of work hardening. This concerns me in testing core actually. I belive that simply cutting a boolit in half, to get to the core....will change the reading of the core. Because of friction from the action of cutting it in half. Either way my cores read softer.

I also size my boolits IMMEDIATELY after casting. I get more consistent results this way. The only trouble with this, is that when the boolit fully "cures", it is slightly undersized. How have i solved this? I reamed out my Lee 452 sizing die to 4525. Or rather I should say I had this done. I don't have the tooling to do that accurately or measure the results. It is, however, a simple task for a local shop to accomplish. Thankfully my uncle is a journeyman aerospace machinist

Rob: i try very hard not to let ego come into play. I would hope that my willingness to take suggestions and open mind will show this. I would like to think that we are all going to learn something and take something away from our discussion. That way we are all winners. I only made the comment about not making friends, to add some levity to the matter. i like to keep it fun.....

also i am not sure this is entirely off topic yet....that was the reason for my addition of the words "and other factors, which are unknown"......

I try to put a lot of thought into my topics....and leave them somewhat open to drift....

seems to me we are still talking about factors that can and do affect/effect shrinkage

[AriM]

Ay caramba, Ari, that's a lot of questions. Break it down for me so it's easier to address.

You are not mistaken about the instructions given by the maunufacturers of lead hardness testers. But your interpretation might perhaps be subject to an understandable misapprehension. Consider that the instuctions are guidelines and not explanations.

The reason that a small flat is advised is so that the underlying material is not affected by cold working. A small flat cut into the surface will suffice for the test, but a larger flat may result in more cold working, and since the test is one of small degrees, any cold working will confuse the results.

The reason that the base is not recommended for hardness testing, is simply because that area already has been subjected to cold working when the sprue was cut, and so it is not a suitable area for testing.

Cold working causes the indentation to be artificially deepened and widened. Since the test involves tiny measurements and magnification, any degree of work softening will skew accurate test results. A file can work soften the material under it, so it's easy to see that a small flat filed carefully is better than a more extensive flat.

You may wish to read more about the physical mechanism that causes the increase in hardening upon quenching an appropriate lead alloy. It is called grain-boundary strengthening or Hall-Petch strengthening.
http://en.wikipedia.org/wiki/Hall-Petch_Strengthening
http://www.chemie.de/lexikon/e/Grain...strengthening/
Here is a short article on the subject as applied to bullet alloys:
http://www.lasc.us/WiljenArsenic.htm

I do not wish to dodge any of your questions. After you have read-up on Hall-Petch strengthening, please address your questions to me again (maybe a few at a time, so I don't have to type-out a book) and I'll be happy to shed what little light I can.

Good shooting.

I have read the article on LASC about arsenic. Actually many months ago. I will read the articles you link on hall=petch. However, do they relate specifically to lead? Ar rob stated, we know that lead work softens.

Now I did address the issue of a file work softening a flat cut. As well as cutting a boolit in half, to measure core hardness, possibly causing an erroneous reading.

Now I am not so sure I am asking questions here. There are a few, but most are statements, to back up my theory and experiences.

My hallmark question though, is will you be willing to accept the results of a test i conduct on shell vs. core hardness?

I think you have bypassed the articles I linked...let me quote the article again

" Instructions for the tester indicate a flat is to be filed on the side of the test bullet for a contact surface. The initial bullet I tested was a Cast Performance item advertised as heat treated to a BHN 16~21. I wasn't sure how deep the heat treating went, and I didn't want to remove too much material and get an erroneous reading. For reference, wheel weight alloy has a BHN of 9, linotype has a hardness of BHN 22, pure lead is BHN 5.

Heat treating is an easy way to get to a surface hard cast from a softer alloy recipe. The radius of the .458" bullet is large so there is plenty of surface for the indenter ball to make contact, however, I did take two measurements; one without the flat and one with, so I could compare the two and see if filing away the surface made for a different BHN result. The flat cut was approximately .008" deep and the readings were the same. Lee cautions to never check hardness at the base of a bullet as this surface is frequently significantly softer than the sides or nose. The base is typically used to the support the bullet in process, such as hardening, and may not be subjected to the same temperatures and treatment."


It would seem that myself, and Lee precision, and the article they link on real guns, and a few other books and a few other contributors to this thread.....believe that surface heat treating is just that....on the surface....

so my hallmark question....if I provided a documented test to show that cores are in fact softer than surface layers....would you be willing to rethink your theory? or are you 100% positive already? because more than a few people disagree/agree with BOTH of our conclusions.

If you are willing to take the time to read all of my posts. Since I was willing to take the time to write them. Then maybe we will both learn something. If the relationship here is that you want to tell me the way things are, then no further dialogue is necessary. I am willing to have an open mind, but not willing to take the time to discuss....if you have that opinion of our dialogue.

I appreciate the suggestion of running the melt cooler. that is logical and I will try it. I do not think it is fair though, for anyone to come to the thread and try to tell me it is the way is. i would like for us to ALL be open minded.

As I said I am willing to conduct the test. If it's too much trouble to continue the conversation, then I also understand. No hard feelings.

I will accept advice, and accept suggestion and have an open mind. I do, however, refuse to be talked down to. I hope that we are standing on equal ground.

[sagacious]

I will accept advice, and accept suggestion and have an open mind. I do, however, refuse to be talked down to. I hope that we are standing on equal ground.

Whoa. OK. This is where I leave the discussion to others. I have not talked down to anyone, and this discussion has taken a sudden unpleasant turn.

Best of luck with your experiments. I wish you well.

[AriM]

I can prove this wrong, and I've done the testing. Heat treatment hardens more than the surface.

he clearly says he has proof....I am asking for the proof

I see nothing along the lines of what you suggest

If you are going to quote someone, and then try to use it as ammunition against me....then please quote the entirety of what they said....and the entirety of what i replied with.....not just the parts you find help your cause....it's only fair

[AriM]

Ari,
I'm not suggesting anything. I'm just responding to the above-quoted excerpts. I am content to leave the discussion to others if my comments are seen as contentious. I do not intend to be contentious in any way.

Occasionally, someone will make a claim, and then challenge others to disprove it. Happens here from time to time, poses an unfair and irrational challenge, and sometimes derails the discussion. It's like saying, "Flying saucers are from Mars. Don't agree? Then prove me wrong"

Even the slowest intellect will immediately recognize the problem withg that reasoning.

Again, I'm not preaching, just saying. Good luck!

you say you aren't talking down to me?

hmmm.....as you said....I think the discussion is not productive between you and I....you are clearly talking down to me....

I am willing to conduct tests to reach a mutual conclusion....but you don't seem to want to answer me....would you accept those tests....

it's not an issue of taking an ugly turn....it's an issue of me being open minded and then you making the statement you made above (that I highlighted in red)

if that is not contempt....then i am not sure what is

either way thanks for the suggestion on the mould issue

I would still be willing to run the test...for both of our benefit, but it seems you already have your own truth....which nothing would change

too bad...I liked our initial dialogue

[Frozone]

Now I did address the issue of a file work softening a flat cut. As well as cutting a boolit in half, to measure core hardness, possibly causing an erroneous reading.

It does. Harden it to around 30bhn and squeeze it in a roll crimp. Because 30+ is very brittle, it will break clean at the crimp line and you can check the hardness across the cross section - You'll find it only varies by a small amount.