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

[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!

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!

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_Chap...Metallurgy.htm

[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.