"optimum" Brinell hardness & Missouri Bullets - WARNING - MATH !

[Bookworm]

I was perusing the Missouri Bullet Co. website, and came upon this is the "technical" section. They claim that there is a formula to calculate the correct BHN for a given load, if you know the CUP for that load. For those interested, here is the link -
http://www.missouribullet.com/technical.php

What it says, is that the formula for the correct BHN is "Optimum BHN = CUPS/ (1492 x .90)",
which is a longer way of saying

BHN = CUPS/1279.8

There is a published load on Hodgdons site, 200gr LRNFP with7.8gr Universal is 15,400 CUPS (and 1045fps from that barrel)

So, according to them, my load of 7.5gr Universal under a 200gr LRNFP needs a BHN of just under 12. I am shooting that load with a boolit that tests at that BHN, and getting a very small amount of lead at the forcing cone, but I think that's a forcing cone issue, not a load/lube/boolit issue. That will be a completely different thread.

Anyway, there is no explanation on the site about what that number (1422 x .90) represents. For all I know, they picked it off a price tag on a used fleece parka at the local resale shop.

My question is basically ..... uh.... really ?

- anybody familiar with this formula ? any idea from where it came ?
Anybody ever use it ?

What the heck does that number (1422 x .90) represent ? ?

Comments ?

[jgh4445]

The "correct BHN" to do what? It's one thing to penetrate paper, another to penetrate 8 inches into a PO'd Grizzly.

[Bookworm]

"optimum" according to them -


An optimally hard lead bullet is simply one which obturates at a given pressure sufficiently to seal the bore against the gases which would otherwise “cut through” the soft lead (called “gas-cutting”, forcing molten lead into your rifling. A bullet which is too hard won't obturate and seal the bore, because the gas pressure is insufficient to expand the base of the bullet. A bullet which is too soft at a given pressure will experience excessive base expansion and vaporization of the lead, causing leading.

cut and pasted from the page

[dragon813gt]

Lee has the same formula on their manual. At least I think it's the same formula. I know one is in there.

As to MBC. In reality they use a high BHN and hard lube to keep their product from being damaged during shipping. They can post whatever they want on their site. But that's the reality of why they do what they do. If they sold optimal cast bullets they would be a larger diameter, softer alloy and use a softer lube.

[C. Latch]

"optimum" according to them -


An optimally hard lead bullet is simply one which obturates at a given pressure sufficiently to seal the bore against the gases which would otherwise “cut through” the soft lead (called “gas-cutting”, forcing molten lead into your rifling. A bullet which is too hard won't obturate and seal the bore, because the gas pressure is insufficient to expand the base of the bullet. A bullet which is too soft at a given pressure will experience excessive base expansion and vaporization of the lead, causing leading.

cut and pasted from the page


Not a word in there about sizing.

See dragon's post above mine. I think your answer is there.

[mdi]

I read about and tried "The Formula" a few years ago. I went through all the mixing, testing BHN, and sizing, but the only part of that exercise of any worth was the sizing. I could not tell any difference with hot loads of one BHN (soft) to another (hard). But all my bullets are sized to fit the gun they will be used in, so I beat the leading problem that way, long ago...

[44man]

Figures!!!!. Too much works but my problem is make the boolit softer to "obturate."
If a boolit is .431 for a .430 groove why bump a boolit to .457 or whatever brass can take? If a barrel will take .430" to .432" just why would you make powder make them larger? Did they not fit?
Darn, forgot about expansion after pressure drop to seal skid. Happy days found well down the bore!
Hard boolits do not seal is another dork thing. Sorry, lead can not be made hard enough to not expand. I wish the hard boolit causes leading would go away.
How does a rivet head on a boolit work?

[Maven]

Bookworm, Your point has baffled others as well. Here's a quote by Joe Brennan (aka joe b.) from our archives, which attempts to explain "the math":

BHN and Pressure
A quick internet search shows dozens of sites where success in shooting cast bullets is equated with some relationship between the hardness of a bullet (BHN) and the chamber pressure in the gun.
One relationship is that BHN * 1422 should equal pressure.
Another is that pressure should be between BHN * 480 * 3 and BHN * 480 * 4.
The word "obturation" is often mentioned.
BHN is the ratio of: force applied to a ball in contact with the test material for a given time; to the area of the semi-spherical indentation in the test material made by the ball. Units are kilograms and mm squared. Converting to pound-feet units, we find that BHN * 1422 expresses the ratio in pounds and inches squared.
Now 1422 looks like the 1422 in the first relationship above, and like the 480 * 3 in the second relationship. (480 * 3 = 1440)
The BHN testing dimple/crater/indentation area in the test material and the force applied for a given time have nothing that I can imagine to do with peak or average or initial chamber pressure.
So the contention is that for a given pressure, if BHN is too low, something bad happens, (I can't find out what), and if BHN is too high the bullet won't obturate-gas leaks by and the gun leads.
Does anyone out there have any information or data supporting this?

[Tom W.]

Uhhhh......o.k.

[Bookworm]

Maven -
I appreciate the read. I read it 5 times, and it appears that 'joe b.' goes way around the bush to ask the same question I did.
He had different "magic numbers" than I, but the same question.

I understand that lead needs to be soft enough to "grab" the rifling as it goes down the bore, yet hard enough to not "strip" as it does so.
I even understand that there must exist some mathematical relationship between pressure and required lead hardness to not "strip" the lead onto the rifling. That relationship has to take into account the twist-to-bore-diameter ratio. The formula may or may not exist, and these "magic numbers" appear to be an attempt to make that formula work.
Apparently the formula doesn't really exist, or is not fully understood. Ballistics is about 50-50 science and black magic. I was looking for an easier way to develop loads.

Looks like it's back to the old trial and error. "load 'em, shoot 'em, clean 'em, repeat". Just means I have to shoot more.

What a shame...chuckle... never really liked math anyway.

[Maven]

Bookworm, I found joe b's response while looking for Steve Hurst's articles in the "Fouling Shot" (CBA). Hurst tried to explain the math and reasoning behind it in order to determine bullet BHN & pressure relationships. Unfortunately, those are old articles and Google wasn't much help.

[MSD MIke]

I have never had any luck with any commercial bullet. They have all leaded my guns even if the size is proper. I cast my own and life is good. The three obvious differences are soft COWW lead, soft lube and square bases. One day when I retire I will have the time research and test those differences individually. None of this matters unless bullets and throats are of proper size.

Thanks
Mike

[runfiverun]

even Richard LEE didn't explain it while he was explaining it in his book.

I just ignore it and do what I want, sometimes it don't work.
usually it does waay beyond what those figures say it won't.
it isn't because they ain't right but I believe it's because it don't work that way.
think about it, shove something in a hole and push on it, it might try to get shorter or whatever.
but what ultimate shape will it take [a cylinder] get your boolit pretty close to that shape and allow it to flow a little closer to that shape under launch.
and what happens.
you destroy less of the boolit or alter it's shape less towards the ultimate compressibility shape in a barrel.
thus being able to push it harder than normal without upsetting the balance.

okay now the alloy part.
did you know antimony crystals break down inside a lead alloy and allow the lead to flow easier under pressure?
think about that.
the uber hard alloy is actually able to slump easier under pressure.
combine that with areas of non support and throw in some rotation.

1422 X Bent = Jack..... on paper.

[Bookworm]

okay now the alloy part.
did you know antimony crystals break down inside a lead alloy and allow the lead to flow easier under pressure?
think about that.

Now that I did not know. It does explain, however, why Babbit Alloy is so high in antimony. I never really understood why it was so. I suppose I could have asked my sister (the metallurgical engineer), but I don't know if that was within her scope of work. I cannot tell you how much I have learned just reading on this site.

[Bookworm]

I have never had any luck with any commercial bullet... The three obvious differences are soft COWW lead, soft lube and square bases.... None of this matters unless bullets and throats are of proper size...
Mike

This is true. I was not having problems with a commercial bullet, I was just perusing the website. I was getting some leading on one side of the forcing cone, just at the entrance to the barrel. I believe the cylinder is out of line, causing the bullet to "clip" the barrel edge on the way into the forcing cone. I actually dug bullets out of the dirt and examined them to reinforce my suspicion.

My Super Blackhawk Hunter is on the Brown truck, even as I type. It's on it's merry way to Long Hunter in Amarillo to get a bit of work done, including reaming the forcing cone to 11° and opening the cylinder chambers. Hopefully it will be back, 'ere too long.

I miss it already.

[Harry O]

The 1422 number is an old one and is used in engineering all the time (converting Bhn from Kg/mm2 to lbs/in2). It closely predicts the yield point (or yield strength) of metals. Once you go over the psi number, the metal will NOT return to exactly the same shape as it started as. That means that when you go over that psi number in the chamber, the base will NOT return to its same shape when it leaves the muzzle. This may have an effect on accuracy, and may not.

It is not a be-all and end-all. The longer the excess pressure is applied (like in rifles), the more deformation there is. The higher the excess pressure is applied, the more deformation there is. I use that number as a starting point when I handload. That is one variable I don't have to worry about. I can increase it from there. Sometimes I can go a fair amount over. Sometimes not. I believe that is because of a number of variables I don't have much control over (such as barrel diameter, straightness, smoothness, chamber/throat dimension, consistency of the rifling width, etc).

Anyway, anyone who says it is BS is going against 75 to 100 years of engineers using it in the real world. Like most things in engineering, the equations are guidelines or strong suggestions. They are not the final word.

[Maven]

Good explanation, Harry O!

[44MAG#1]

"The 1422 number is an old one and is used in engineering all the time (converting Bhn from Kg/mm2 to lbs/in2)."

How do you that 1422 number to convert the pressure of a 44 Mag, for an example, to pressure to BHN. Let's say I want to use a load that suppose to generate 36,000 CUP.

I am sure Elmer Keith, Skeeter Skelton, Ray Thompson and a host of others used that formula in their casting and shooting.
They can't be wrong.

[Bookworm]

Harry O, what I think you are saying is that the "magic number" is a Constant. The same as pi is a Constant.
Also, the reason it isn't exact is the myriad variables with which it interacts. For instance, I ran a load with a CUP of 36000 through it, it came up with a ridiculous BHN of something like 26 .

Okay, I can accept that. It certainly clears up my original question.

It's more fun, however, to call it black magic....

[DougGuy]

If you have a Ruger SA revolver, in .44 or .45 caliber, and you shoot heavy for caliber boolits, alloy that is soft enough to scratch with a thumbnail works GREAT! What is this BHN12 or thereabouts? Soft lube like Felix, gas checks, this 50/50+2% alloy is a match made in heaven for a Ruger barrel. Nobody needs a formula, right here is the formula. Try it, and enjoy never having to clean a bore again..

[runfiverun]

the one thing we forget to factor in when compressing the base of boolits is that the unlead spots [lube grooves] are a liquid under pressure and heat.
this is why I fill the area above the gas check with lube.

even Elmer believed that the base of the boolit being compressed by gas pressure would hydraulic the lube outwards onto the barrel face.
we have to remember Elmer wasn't an Engineer he was just good at observing things and thinking his way through what he was seeing.
pretty good writer too.
but he was basing his predictions and changes on observation.
we can all do the same exact thing.

[Harry O]

One question was, how do you use the 1422 number. First of all, where did it come from. There are 25.4mm per inch. Pressure is in square mm or in. There are 2.204lbs per kilogram. (25.4 x 25.4 x 2.204 = 1,421.9) or, 1,422 rounded off.

If you have ingots with a known Bhn and want to know what pressure you should start experimenting at, take that Bhn x 1,422. For example, Bhn 12 (a common mix I use for non-magnum cartridges) x 1,422 = 17,064psi. That means that you can start with 17,000psi pressure and work up from there until the accuracy goes bad. Accuracy usually goes bad very quickly when it exceeds the limit of your gun dimensions, bullet hardness, bullet pressure, and bullet lube limit. With my S&W's, I can usually go to about 21,000psi before accuracy drops,

On the other hand, if you have a pressure from the load you want to use, you can work backward to find a Bhn. For example, if you want to use a 28,000psi .357 lead bullet Magnum load, divide that by 1,422. (28,000 / 1,422 = 19.7 Bhn) I have a bunch of monotype, so I can hit any Bhn up to 28.

Just so that you know, I have found that with my guns, I can get down to Bhn 18 with a 28,000psi load without any accuracy problems. Softer than that will cause a problem with my Ruger, but the Colt and S&W's can go just a little lower than that. I just stick with 18 so it will work in anything.

Remember what I said before. This formula is not gospel. The numbers this formula gives are a good starting point. You can either stop there and be happy without further experimentation or lean the mixture until it doesn't work anymore. Then harden it just a little bit until the accuracy comes back and be happy at that point.

[44MAG#1]

Does it matter,if it is CUP or PSI? What if it is a 40,000 CUP load or a 36,000 PSI load?
So if a person is going to run 36,000 PSI the required BHN would be 25.
But if we used the 40,000 CUP figure we would need 28 BHN.
Talking about the 44 Mag now.
Now if we wanted to use an alloy of 1-16 which I think runs around 10.5 it would require a minimum of 14921 PSI to Obturate the alloy?
What if we want to run that alloy to 30,000 PSI?
Would we be out of luck?

[HangFireW8]

Does it matter,if it is CUP or PSI? What if it is a 40,000 CUP load or a 36,000 PSI load?
So if a person is going to run 36,000 PSI the required BHN would be 25.
But if we used the 40,000 CUP figure we would need 28 BHN.
Talking about the 44 Mag now.
Now if we wanted to use an alloy of 1-16 which I think runs around 10.5 it would require a minimum of 14921 PSI to Obturate the alloy?
What if we want to run that alloy to 30,000 PSI?
Would we be out of luck?

That's a lot of questions. I'll address what I can.

1. For the 45/70, CUP == PSI, because that's where CUP was developed, and they got it right. As you go to more bottleneck, higher pressure, and more overbore cartridges, the divergence of PSI to CUP becomes more pronounced. For the 44Mag, its straight-walled and large bore resemblance to the 45/70 means that, for pressures that parallel the 45/70 anyway, there's not a whole lot of difference between CUP and PSI.

2. "So if a person is going to run 36,000 PSI the required BHN would be 25." The required BHN for what, exactly? Don't say "obturation". It's the required BHN for matching THE FORMULA, and that's about it.

3. "Now if we wanted to use an alloy of 1-16 which I think runs around 10.5 it would require a minimum of 14921 PSI to Obturate the alloy?"

Please realize there are other ways to obturate the boolit without meeting the pressure dictated formula. For softer, slightly undersized boolits, lead displacement by plastic deformation can cause obturation into the grooves at pressures far below THE FORMULA. For oversized boolits, extrusion caused by shoving the boolit into the throat can do it as well.

The entire body of the boolit does not need to be deformed by pressure for obturation to occur, which is why THE FORMULA is not as useful to cast boolit shooters as it seems it should be. If the localized forces on the outer skin of the boolit engaging the throat cause it to deform enough to obturate, then the pressure on the base of the boolit can be lower, as long as it provides enough momentum to get the relatively small engagement area to deform.

On an unrelated note, this is why I am not overly concerned with sizing water dropped boolits causing a loss of BHN. The loss of BHN is localized to the tops of the bands, which get deformed anyway. The core of the boolit is still at the higher water-dropped BHN, which gives it the strength the prevent nose slump, maintain bore center and for allow higher velocities. (Higher, but maybe not the highest, where oven hardening may be best).

That last statement will be found controversial by those reading Fryxell and taking too much of his truths at face value, without questioning the small details.

[44MAG#1]

"That's a lot of questions. I'll address what I can.

1. For the 45/70, CUP == PSI, because that's where CUP was developed, and they got it right. As you go to more bottleneck, higher pressure, and more overbore cartridges, the divergence of PSI to CUP becomes more pronounced. For the 44Mag, its straight-walled and large bore resemblance to the 45/70 means that, for pressures that parallel the 45/70 anyway, there's not a whole lot of difference.

2. "So if a person is going to run 36,000 PSI the required BHN would be 25." The required BHN for what, exactly? Don't say "obturation". It's the required BHN for matching the formula, and that's about it.

3. "Now if we wanted to use an alloy of 1-16 which I think runs around 10.5 it would require a minimum of 14921 PSI to Obturate the alloy?"

Please realize there are other ways to obturate the boolit without meeting the pressure dictated formula. Lead displacement caused by shoving the boolit into the rifling can cause obturation at pressures far below THE FORMULA."

That is answering a lot of questions but you left out this one:
If we want to run that alloy to 30,000 PSI?
Would we be out of luck?

[HangFireW8]

If we want to run that alloy to 30,000 PSI?
Would we be out of luck?

Sorry, I'm a cast rifle shooter not a 44Mag shooter, and I don't have another formula to substitute for you.

[44MAG#1]

"Sorry, I'm a cast rifle shooter not a 44Mag shooter, and I don't have another formula to substitute for you."

Could we run the 1-16 alloy to 30,000 PSI or would it wind up being a horror story?
30,000\1422=21BHN. But the 1-16, if memory serves me correctly is 10.5 or there about.

[HangFireW8]

"Sorry, I'm a cast rifle shooter not a 44Mag shooter, and I don't have another formula to substitute for you."

Could we run the 1-16 alloy to 30,000 PSI or would it wind up being a horror story?
30,000\1422=21BHN. But the 1-16, if memory serves me correctly is 10.5 or there about.

Guess what? You're still asking for specifics, and I still don't have a formula for you. I take the easy path and use suitable alloys for their respective purposes, which does mean harder for faster/higher pressure.

I'm guessing with a gas check and a flat-nosed boolit, and many other factors under control, it could be done. Doing it in a revolver would make it harder. Keith got his 44 Special load to 27K PSI, and I think he was using 1:16. Some research on this board would be the place to start, but I'm not interested enough, as I have plenty of high antimony alloys lying around.

[44MAG#1]

"Keith got his 44 Special load to 27K PSI, and I think he was using 1:16."

Also Keith wrote that he used 1-16 in the 44 Mag too which had a pressure higher than the 44 Special.
He called that his hard cast bullets.

[runfiverun]

factories run 40-1 alloy for about 100 years in stuff like the 44 mag and 45 colt.
so somehow they got 6 bhn alloy to 14-k and up into the 35-k area.
granted the 35-k area was too much and many times the barrels leaded up.
nobody bothered to really look at how a 429 boolit was working in their mis-matched revolver or at their 430 barrel.
but they were sure quick to blame the hardness of the alloy.
I'm pretty sure this combination and the same one they used in the 357 mag has caused a litteral metric ton of wive's tales that stil live on today.

[jonp]

"


The formula (from the pages of HandLoader Magazine) to determine at what pressure an alloy of given BHN will obturate the base of the bullet and seal the bore. If the bullet is too hard to obturate, gas cutting usually occurs on the base band on the non-driving side of the rifling and barrel leading is likely. Simply multiply the alloy BHN by 1,422.


Example: Alloy BHN of 12 multiplied by 1422 = 17,064. An alloy of 12 BHN should be used with a load that develops a "minimum" of 17,000 psi. Need more info on minimum / maximum alloy BHN? These Glen E. Fryxell articles explain alloy BHN in easy to understand language. "

From Castbullet Notes link at the bottom of the page. I've used it as a starting point and it seems to be a good rule of thumb as a place to begin but I don't think it's "optimum". Missouri does make some good boolits, though. I believe what they wrote is just press to talk up their product.

[44MAG#1]

The first I ever read about the 1422 figure and the relationship it had to BHN and chamber pressure was in my
"Jacketed Performance With Cast Bullets" by Veral Smith that was copy written in 1984. With the third edition copy written in 1990.
The book was nice reading too.
I had the first copy and got the third edition too just after he did it.
Got my first molds from him when he was in Arizona. Probably in around '86 or so.
Still I guess people can use the soft alloys with fairly high pressure if one matches everything. Right.
I know I do occasionally. I also use hard most of the time water quenching nearly everything.
Figuring all this stuff gives one something to do when they are bored. Especially the new people in the casting thing.

[Bookworm]

OP here. And, I'm one of the "new people in the casting thing". However, I started reloading in the late 80's.

So, reading this ton of info, I am changing my opinion of The Formula. That 1422 number is not a Constant, as I thought earlier in this thread, several days ago. The way that it has been explained is that the number is a conversion factor. That makes more sense to me, and I appreciate the info on whence it came. At least now I know it's not random.
Also, it appears that The Formula is merely a starting point, a guide. Not the end-all and be-all. Fabulous.

I am constantly amazed at the amount of information and experience on this forum, freely shared among like-minded individuals.

A veritable cornucopia a knowledge. An enormously valuable resource.

Thanks to all for spending the time to type it all up, and explain it in a manner that is understandable.

[Harry O]

A few things about Elmer Keith and his .44 Special/.44 Magnums. As was stated above, his hot .44 Special loads were in the 27,000-28,000psi range. He used plain base bullets. I can also load to that pressure with plain base bullets. He originally used 16:1 lead:tin mix with them. If you read his books, he fully expected some leading with that. The cleanup was not difficult. Some time later, he changed to 10:1 lead:tin mix. I probably think that it was when he went to .44 Magnum loads at higher pressures than his .44 Special loads, but don't know that for sure. If he went to full .44 Magnum loads, I would expect that he would still have some leading with even 10:1.

The pressures mentioned above (36,000 to 40,000psi) are outside plain base bullet territory as far as I am concerned. That is smack dab in the center of gas-check territory. I regularly load .357 Magnums to that pressure with a 358156-GC without any accuracy or leading problems. If you want to shoot in that territory with plain base bullets, be my guest. I won't waste my time trying that anymore.

I did try a plain-base bullet at 42,000psi once. There was no gas-check available in that caliber and nose shape. I cast it from straight monotype. That did not work at all. It was too brittle to even feed through the action. I melted the bullets down again and added enough tin to equal the antimony. It ended up about 70% lead, 15% tin, and 15% antimony. I dropped them into water when casting. The bullets were ductile enough to feed through the action and had reasonable accuracy. However, it was a ***** to cast with, a ***** to size, and was very hard to test for Bhn (near as I could test, it was in the upper 30's for Bhn). After checking the price of the bullet made from monotype and tin, I found that I could buy factory-second, jacketed Hornady soft-points, for the same cost as cast without all the BS of making them.

So I quit trying to use plain base bullets at high pressure. You are welcome to do as you wish. I use Bhn 12 plain-base for up to about 20,000-22,000psi. I use Bhn 18 plain-base for up to about 30,000-32,000psi. Neither of those is exactly per the formula. However, I started with the formula before experimenting to these limits. Above that I use gas-checks up to about 42,000psi. Above that I use jacketed bullets. That works for me.

[44MAG#1]

"Some time later, he changed to 10:1 lead:tin mix. I probably think that it was when he went to .44 Magnum loads at higher pressures than his .44 Special loads, but don't know that for sure. If he went to full .44 Magnum loads, I would expect that he would still have some leading with even 10:1."

In Keiths book Sixguns he related in the addendum chapter concerning the birth of the 44 Mag he used 1-16.
I have been a huge follower of Keith and I can tell you that he recommended 1-10 in auto loading handguns.
The pictures that he showed in the chapter on the 44 Mag was bullets that were 1-16 shot into range bulls heads.
Do as you wish. I know I will.

[sniper]

O.K., Marvelous thread...I think...the knowledge is amazing! But...howcum I am as confused as I was before?

When I was young and immortal, knowing nothing about BHN or much else, I shot IPSC with home cast boolits... 150gr. RCBS mould / Coleman camp stove, with what I dearly hoped was somewhere in the neighborhood of Lyman #2, adding wheel weights, 50-50 bar solder, and scrounged lead. I pan lubed with the sticky, red stuff that Lee sold with its .357 sizer. 860 fps chronoed NO LEADING...ever!

Then, I stopped casting, and bought some commercial"hard cast" boolits from a local supplier. Same load...leading out the wazoo!:shock:

Now, I know about BHN, but, math makes my head hurt, so I am probably the only one on the forums who is still confused! I am looking at different suppliers' information...one says "for up to 950 fps", another says BHN 16, Another says "Ours will work!" Confusion![smilie=b:

I am looking for .38 caliber boolits 125/160gr. that will provide minimal/no leading at velocities from ~900-1,000 fps. Lately, I am considering plated projectiles, because they seem less finicky. But, what do I know? Do I just pick a supplier, buy 100 of his boolits, "just to see", until I find something that works? Any recommendations for boolits/manufacturers?

I am thinking maybe lubing whatever commercial cast boolits I buy with something like BLL or White label 45-45-10, and seeing how that does.
Suggestions?

Thanx;
C.

[jmort]

I would try the Missouri Bullets Hi Tek or you can get them unsized and unlubed from Missouri Bullets and use BLL or better yet, start using powder coating.

[Grmps]

http://www.lasc.us/Fryxell_Book_Chapter_3_alloySelectionMetallurgy.ht m

https://i.imgur.com/Cf4PQXQ.png

[RPRNY]

Here's the correct formula: As soft as possible; as hard as necessary.

[reddog81]

Here's the correct formula: As soft as possible; as hard as necessary.

And make sure they're the correct size otherwise you might have problems irregardless.

I like GRMPS chart in post #38 as it shows there is lots of overlap as to what kind of alloys can work over a wide range of loads. For example the 12 BHN can go from light target loads up to magnum loads and still preform well.

[mehavey]

there is no explanation on the site about what that number (1422 x .90) represents.First, one needs to know the definition of a Brinnell #: It is literally the pressure (Kg/mm-sq) at which point the alloy begins to deform.

Take a look here:
http://castboolits.gunloads.com/showthread.php?168469-Brinell-Hardness&p=1886949&viewfull=1#post1886949

The "1422" number comes from converting kg/mm-sq to lbs/in-sq = 1422.332639

The 90% comes from getting real close to (but not over) yield pressure where the alloy just lets go on you.

Be that as it may, however, I've found using a 1.3 multiplier (rather than 0.9) gets me in the ballpark -- adjust from there.
I STRONGLY NOTE: that using a softer alloy is more often than not the best route to go

[cajun shooter]

That posting came from Glenn Fryxell and Ron Applegate's book titled "From Ingot To Target". It's posted in the sticky section and is offered for free to all forum members. It's a must-read for anyone who intends to cast bullets for shooting targets, game or other critters. The book is about 190 or so pages, I downloaded them and then printed them out so that I could put them in a three ring binder as a reference book.
I started loading in 1971 and casting bullets to sell to customers at the gun store where I worked. I always read the articles that Fryxell posted on the forum and even though I had a lot of years of casting, I learned a lot from his writings and still do. His co-writer, Ron Applegate was well known for his mould making abilities for many years . Take Care, David

[sniper]

I found an article that explains the bullet hardness/leading/phase of the moon shimozzle...at least enough to satisfy my confusion. :-D
FWIW....http://www.grantcunningham.com/2008/08/preventing-barrel-leading-in-revolvers-using-cast-bullets/ Sort of like the Pirate's Code....more of a guideline, eh? :wink:

[Mr_Sheesh]

If one was going to get a pin gauge set(s) to go 0.061-0.50 or so, what brands / costs? $150ish or so?

[sniper]

If one was going to get a pin gauge set(s) to go 0.061-0.50 or so, what brands / costs? $150ish or so?

This place seems to have good prices, $20 minimum order. https://www.gageshop.com/product/black-ox-english-class-zz-061-to-500/

[megasupermagnum]

It's this kind of garbage that messes the new casters up. I went through a phase of trying for the "optimal" hardness, and all I got was confusion. That formula means NOTHING at all. There is no way to mathematically calculate how accurate a bullet will be, and there are only very vague suggestions on bullet hardness. According to that formula, I need BHN in the 30's for magnum handguns. I've tried, and am still trying heat treated bullets about 26 BHN, and guess what? Accuracy is no better than 12 BHN. I had to go to to 25-1 alloy before things went south with magnum handguns. Rifles, same thing. I've never heard of anybody shooting heat treated linotype for their old 30-30.

[Mr_Sheesh]

sniper, Thank you.

[dwtim]

Never heard anyone equate accuracy with Brinell numbers. Maybe they mean extreme degradation of accuracy due to a quarter of the bullet being deposited in the barrel?

Anyway, a lot of this doesn't make sense because a) everyone uses whatever alloy is plentiful in their area and b) it depends what the shottist is trying accomplish. I use pure lead scrap, range pick-ups (j-word cores and .22 rimfire bullets, aka 98/2 lead/antimony) and shot. That's all I have available. No tires shops use lead wheel weights here.

What I do may not work for you. Or maybe it does. I make 8-10 BHN alloy that is 90% bullet "core" lead and some other pick-ups. It gives me lead-free performance for 38s/9mm/45s. I can use it for my hot-loaded .357s and .44s, but leading becomes a problem, so I make a harder alloy for those. The third alloy is for rifle--and is water dropped. But If you have wheel weights, read some threads by forum members who use it. It's technically doing an experiment. A good way to fail is to change too many variables at once, so why not use what most of the casters here use, and eliminate unnecessary variables?

Now that I think about it, what makes casting trickier is that reloading manuals deal with absolutes for the sake of safety. It's not that bullet casting is less safe, but more independent thought is required. I think newbies get hung up on those absolutes--for example the common "fact" that lead bullets can't go faster than 1,000 FPS....as if at 1,001 FPS they will explode in a mushroom cloud and destroy your range.

Also: Obturation has a limit. You can't expect a bullet that is exactly sized to .3570 to fill out a .3620 chamber. (Admittedly an extreme example.)

[Rcmaveric]

I use the BHN and pressure relationships to tune loads and play with new powders. It is more of a reference and no so much a hard set rule. I like to use it as means of establishing a starting point. Once you establish a safe starting points that should be reasonably accurate then you can go use the scientific method to tune your own optimal load.

I am similar to dwtim. I use a lot of range scraps. I mix and match to make general purpose alloys of 8, 10 and 12 BHN. Then i calculate min and max pressures. Then i use Quickloads to generate my shot tests that go below and over those pressures. Then i head to the range. The targets will let me know what the gun likes and what is happening to the lead. You will hit a point where the groups rapidly turn into a shot gun pattern. Why those hopefully looking groups degrade can be a any number of reasons besides over pressure though. I have found that the best accuracy is found close to those points of failure.

Now introduce gas checks into the equation and you just changed how much pressure you can put on the leads tail end. So that makes the BHN vs Pressure relationship less of a fact and more of reference for a starting point. There are a lot of things that can change the pressures inside in the chamber and changes the powders burn characteristic with out gaining any velocity.

So for new caster moving into more advanced fields like playing with new powders. I encourage the use of the BHN's for pressures. Like i said though it will to create a safe starting points to start your testing. Most often i find the best accuracy is close to those points of failures and the pressures are normally quite higher than first calculated. But i had to get the conclusion some how. I am also big on the "8 BHN general purpose pistol alloy, 10 BHN general purpose everything alloy, and 12 BHN general purpose rifle alloy" band wagon. There isn't nothing i haven't been able to get shooting good with those.

@Megasupermagnum, you are correct you don't need super hard bullets to get good accuracy. Fit is more important then hard alloys. We all ready know that bullet manufactures use hard lead and hard lubes to make their product survive shipping. Hard bullets are also a band aid fix for poor fitting bullets. I disagree with the concept being garbage though. I think it is great info for new casters. I think we just don't teach it good enough. The reason your 30-30 doesn't need that 26BHN bullets is because it is gas checked and the bullet fits good (i am assuming the fit is good) taking that 25k ish max psi alloy and making more like max 35-39k psi. The 30-30 is also a lower pressure riffle round (42k psi) and its easy to get higher velocities due to the lower pressures. The reason your accuracy is poor with those hard bullets is because they are too hard to obturate efficiently. So you just proved a portion of the theory about the min PSI. There are things that affect the max limit. The alloy content can also affect the leads performance under pressure and its max PSI. You will never know what your alloy can do until establish a test window safely and see what your lead does under those conditions.

[megasupermagnum]

I use the BHN and pressure relationships to tune loads and play with new powders. It is more of a reference and no so much a hard set rule. I like to use it as means of establishing a starting point. Once you establish a safe starting points that should be reasonably accurate then you can go use the scientific method to tune your own optimal load.

I am similar to dwtim. I use a lot of range scraps. I mix and match to make general purpose alloys of 8, 10 and 12 BHN. Then i calculate min and max pressures. Then i use Quickloads to generate my shot tests that go below and over those pressures. Then i head to the range. The targets will let me know what the gun likes and what is happening to the lead. You will hit a point where the groups rapidly turn into a shot gun pattern. Why those hopefully looking groups degrade can be a any number of reasons besides over pressure though. I have found that the best accuracy is found close to those points of failure.

Now introduce gas checks into the equation and you just changed how much pressure you can put on the leads tail end. So that makes the BHN vs Pressure relationship less of a fact and more of reference for a starting point. There are a lot of things that can change the pressures inside in the chamber and changes the powders burn characteristic with out gaining any velocity.

So for new caster moving into more advanced fields like playing with new powders. I encourage the use of the BHN's for pressures. Like i said though it will to create a safe starting points to start your testing. Most often i find the best accuracy is close to those points of failures and the pressures are normally quite higher than first calculated. But i had to get the conclusion some how. I am also big on the "8 BHN general purpose pistol alloy, 10 BHN general purpose everything alloy, and 12 BHN general purpose rifle alloy" band wagon. There isn't nothing i haven't been able to get shooting good with those.

@Megasupermagnum, you are correct you don't need super hard bullets to get good accuracy. Fit is more important then hard alloys. We all ready know that bullet manufactures use hard lead and hard lubes to make their product survive shipping. Hard bullets are also a band aid fix for poor fitting bullets. I disagree with the concept being garbage though. I think it is great info for new casters. I think we just don't teach it good enough. The reason your 30-30 doesn't need that 26BHN bullets is because it is gas checked and the bullet fits good (i am assuming the fit is good) taking that 25k ish max psi alloy and making more like max 35-39k psi. The 30-30 is also a lower pressure riffle round (42k psi) and its easy to get higher velocities due to the lower pressures. The reason your accuracy is poor with those hard bullets is because they are too hard to obturate efficiently. So you just proved a portion of the theory about the min PSI. There are things that affect the max limit. The alloy content can also affect the leads performance under pressure and its max PSI. You will never know what your alloy can do until establish a test window safely and see what your lead does under those conditions.

I cant say accuracy is poor with the hard bullets, it's just that the soft bullets are every bit as accurate. I'm talking handgun, plain base, and according to that formula, I would need a 36 BHN bullet just to handle the pressures. Yet, with no gas check, regular lube, nothing, I get just as good accuracy at 12 BHN. There are variables like different alloys, gas checks, bullet designs, etc, but that formula is so far outside of real world results as to be complete, absolute, useless. It means nothing at all.

[mehavey]

That formula, adjusted using empirical data,is quite useful -- even when throwing gas-checked bullets above 18,000psi for me.

Case in point: 1,422*1.3*15 = 27,700psi ==> which is ~ what I'm running (QuickLoad) in an AR even today.
Armelite M-15/16"/SAECO #221/60gr (Lym#2)/Lyman GC/AA2495/21.0gr/ALOX/2,250fps/honest 1¾" at 100yds

Works unchecked for

- pure lead (BN 4.5): 10,000 psi low-pressure BP cartrigdes
- 30-to1 (BN 8): 15,000psi higher-pressure catridges
- WW (BN 10-11): 18,000 +P loads in 38 Special, 45 Cot
- #2 (BN 15) in the very low 20's unchecked for 45 Colt ++P/44 Mag mid Pressure
- #2 Checked for 25-32,000psi rifles (all calibers)

I've not found ANYthing requiring greater hardness -- and softer/right fit is more often the ticket.

[RedHawk357Mag]

So I assume folks are gathering pressure information used to balance alloy and cartridge loading from Quick Load, Lyman's assorted publications, Hodgdon annual powder publication, and Western Powders publications.
So for instance; page 418 Lyman 50th, #358477, Bullseye 4.6, 17,3 CUP, 7.0, 36,9 CUP. 12 BNH works with the 4.6 grns, 25 BNH works with 7.0 grns, theoretically. So what procedure do you use to cipher your start point for 19 BHN? Does it assume that the progression from 4.6 grns to 7grns is linear? So basically 5.8 grns would theoretically generate 27,1 CUP yielding a start point for 19 BHN. Thanks much appreciated .

[JonB_in_Glencoe]

RedHawk357Mag,
That is exactly how I begin figuring out what alloy I want for a specific load. I realize pressure probably doesn't rise in a linear fashion...but I can find a place to start (assuming I have a target speed I am trying to obtain) to work up a load for Rifle ammo ...or if it is for pistol ammo, it isn't nearly as critical, I am able to get close enough (with BHN) for the desired load with that technique.

[popper]

Hard alloy does not cause leading. Soft alloy does not cause leading. Gas cutting will deposit lead in the bore. Lube that liquefies will provide hydrostatic block to gas cutting force (tumbled LLA won't work). Soft alloy will shear on the lands at a higher pressure than initial oburation.