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

[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/show...=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.
FWIW....http://www.grantcunningham.com/2008/...-cast-bullets/ Sort of like the Pirate's Code....more of a guideline, eh?

[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/bla...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.