Bhn ?

[Digital Dan]

It occurs there are different alloy mixes that will present the same BHN, example being simple lead/tin mixes and lead/COWW mixes with emphasis on lead with just a bit of COWW.

Question that arises, can one expect the same performance with say 30:1 (~9 BHN) and lead with just enough COWW to raise it to 9 BHN?

Anyone know?

[pjames32]

You can reach 9bhn with or without antimony. You need to decide if antimony is needed for hardness?

[Digital Dan]

Rephrase of the question: I have two alloy mixes, one with known constituents, the other is unknown. They have the same hardness, 10.4 BHN. Is it reasonable to expect the same performance even though I'm quite certain the alloys are different?

[OptimusPanda]

Rephrase of the question: I have two alloy mixes, one with known constituents, the other is unknown. They have the same hardness, 10.4 BHN. Is it reasonable to expect the same performance even though I'm quite certain the alloys are different?
Are they the same weight from the same mold?

[Oklahoma Rebel]

no, the one with more tin will deform without being as prone to fracturing as the one with antimony, even though they are technically the same hardness, they will behave differently. they will also weigh differently, though im not sure in this situation which one would be lighter/heavier. does that answer your question? have a good day, don't be afraid to ask any more questions-Travis

[Digital Dan]

Was more concerned with the interior ballistics side of the equation than terminal or exterior. Should have clarified that

[Harry O]

They will act differently. The one with tin will cast easier, shoot to a higher velocity without leading, and expand better in game. However, it will cost more. The one with antimony won't do quite as well, but it is cheaper.

[Digital Dan]

Thank you sir!

D

[Larry Gibson]

Harry O is essentially correct. BHN is only one half the equation, the alloy malleability is the other half.

Larry Gibson

[Crusty Deary Ol'Coot]

Digital Dan,

Some good answers here but ---------------

Then the question comes, what are you shooting it in and what is the end goal?

Crusty Deary Ol'Coot

[Digital Dan]

Ol' Coot, actually the question isn't so much what I'm shooting the alloy in so much as what I will shoot it in. Having mentioned previously that I've mixed a number of alloys for various purposes in the past which I refer to as Lyman #2, Dan's 1.75, 1.5 and 1.25. It occurred that I inherited some lead from a fellow and found one to have the same BHN as my 1.5 alloy, or 10.4. Haven't a clue what the constituency is, but will load it and see what happens.

Now I play eenie-meenie-miney-mo... .25-20, .30-30, .44, .38-55 and well that takes care of the squill guns....

[runfiverun]

the total make up of the alloy will determine how it reacts to being shoved forward under pressure.
9 bhn can be arrived at by at least 5 different alloy make up's, but so can the peak pressure your going to attain.
each alloy and pressure rise speed/sustainability time will react differently.
antimony isn't the bad guy and tin ain't always the good guy, and a mix of the two changes things considerably versus each one alone being used.

[Digital Dan]

runfiverun, in very general terms I understood that part about the pressures, just wasn't clear about how the alloy would react. Might be an indicator that I had half a wit and thought to ask the question, maybe...there's a quirk or three in the landscape that gave a hint that 9 ain't always 9, and 1+1 adding up to 2 might be true, or not....

As example, quite some time back a fellow I respect in the shooting world suggested I get over the hardcast theory and that was excellent advice. More recently I discovered that a fairly soft alloy successful at moderate velocity was prone to leading at low velocity. Didn't obturate I guess, if only because softer alloy worked fine with the same charge and velocity. Wish I'd learned this when I was 10.

On a lighter note, if you work on that prose a little you could make a caster's rap song (?) out of that. Made me smile.

This is what happens when you start with PB, Sn, COWW and Linotype in inventory then some well meaning soul gifts you a pile of mystery metal.

[mehavey]

BHN is -- by definition -- the force (lbs) per square inch at which a material will deform.
Nothing more. Nothing less.

For those families/alloys of metals commonly used for bullets: equal weight bullets of equal hardness/design will perform similarly when shoved down the rifled barrel under equal pressures.

[Larry Gibson]

"For those families/alloys of metals commonly used for bullets: equal weight bullets of equal hardness/design will perform similarly when shoved down the rifled barrel under equal pressures."

Probably a good rule of thumb for cast bullet use under 2000 fps. However, above that there can be a difference in performance (accuracy) under the same load and pressures. Case in point; AC'd linotype alloy bullets have the same BHN as WQ'd Lyman #2 alloyed cast bullets....21 - 23 BHN +/- yet, at HV, there is a distinct difference in performance when cast of the same design and pushed at the same pressures. There are other examples.

Larry Gibson

[mehavey]

Can't argue that things may go a bit non-linear past Mach-2.
i'll dig into it a bit more (I'll admit 2,200 is my max w/ #2/ALOX
at 15, but then I stay moderately Holiday Inn Express simple)
:veryconfu

[mehavey]

it suddenly struck me that water-quenched alloys are structurally different than normal/air-cooled bodies, which have uniform hardness throughout. The WC'd bodies have relatively thin superhard crystaline shells on the surface -- think case-hardened -- while the interiors are soft.

I would indeed expect such bodies -- uniform vs thin-shelled -- to behave differently under extreme (especially rotational) stress.

[blackthorn]

it suddenly struck me that water-quenched alloys are structurally different than normal/air-cooled bodies, which have uniform hardness throughout. The WC'd bodies have relatively thin superhard crystaline shells on the surface -- think case-hardened -- while the interiors are soft.

I would indeed expect such bodies -- uniform vs thin-shelled -- to behave differently under extreme (especially rotational) stress.

Could you please expand on the above? I would like to know how (based on what) you arrived at that conclusion.

[mehavey]

Before we get to the rotational differences between uniformly-hard bodies, and bodies having non-linear hardness, could someone point actual measurements of quenched Lyman#2 please ? (Rotometals, so true #2)

I just poured two 530gr postells, and dropped them directly into ice water.

Cut in half, and measured over three depressions each, the interior mid surface measured 14.9
The exterior measured (gasp) 15.

[Larry Gibson]

mehavey

What you discovered through actual testing is the common alloys used in bullet casting when WQ'd or HT'd do not "case harden".....they actually harden all the way through. Lyman #2 WQ's to 21-23 BHN. Like many things we do there are variables so giving a 22.7 BHN, for example, would be somewhat incorrect.

Larry Gibson

[mehavey]

But Larry, the Lyman#2 did NOT WQ harden.
It stayed at its normal BN-15.... inside and out.


Like many "settled cast bullet science" things I find on the internet... does anyone else have actual data ?


BTW: I've found/used this really neat Celestron microscope to measure the Brinell impression w/ some precision:
https://thefiringline.com/forums/showpost.php?p=6103326&postcount=7
...vice the old-fashioned way:
https://thefiringline.com/forums/showpost.php?p=6102758&postcount=5

[Larry Gibson]

How long after casting/ WQing did you make your BHN measurement? Also when WQing large bullets it is imperative the sprue be cut immediately on solidification and the bullet dropped into the water immediately. The alloy should be hot also....725 +/-. The fact your bullets didn't harden indicates they went into the water not hot enough to harden or you're measuring before the alloy fully hardens.

Larry Gibson

[mehavey]

Cast at 750 (thermometer) and dumped directly from mould to water (w/ ice).

That there was NO hardening -- AT ALL -- makes me truly wonder if there is actual data on real 90-5-5 alloy, or whether mongrel mixes were used that had the classic wheel-weight/arsenic component -- in which case all bets are off.



I'll reheat some in the oven at 475 (lasc-style) then water dump to see what happens.

[JonB_in_Glencoe]

Like many "settled cast bullet science" things I find on the internet... does anyone else have actual data ?
I don't use 90-5-5
I do use 94-3-3, this is real 94-3-3, (not COWW with 2% tin)

Here is a test I did with 94-3-3
http://castboolits.gunloads.com/showthread.php?248671-Heat-treat&highlight=

[Larry Gibson]

Like I said, my WQ'd #2 alloy bullets have a BHN of 21 - 23 after 24 hrs. I use analyzed linotype, pure lead and pure tin to make correct #2. You asked a question, got an answer. Obviously the answer isn't the one you want. Lots of actual info/data on the subject........some other is provided.........

Larry Gibson

[mehavey]

Larry, Larry, Larry...

Like I said in the last post, I did the lasc oven trick last night w/ some #2 heated for 30 minutes at 475, then dumped in ice water.
This morning it measured BHN 21.
So there.:holysheep :oops:

[Larry Gibson]

Larry, Larry, Larry...

Like I said in the last post, I did the lasc oven trick last night w/ some #2 heated for 30 minutes at 475, then dumped in ice water.
This morning it measured BHN 21.
So there.:holysheep :oops:


Great, so now you know Lyman #2 does in fact harden. Obviously you're just not doing something right in your WQ technique. Odds are the bullets are cooling too fast before you get them into the water or you were just measuring the BHN before the hardening had fully occurred. Glad you met with success at least with one method......:drinks:

Larry Gibson

[JonB_in_Glencoe]

Larry, Larry, Larry...

Like I said in the last post, I did the lasc oven trick last night w/ some #2 heated for 30 minutes at 475, then dumped in ice water.
This morning it measured BHN 21.
So there.:holysheep :oops:

I would recommend a full 1 hour Heat treat, you will achieve more uniform results throughout the boolit (and batch of boolits). I believe it takes that much time to fully dismantle the former crystallization, to allow new crystallization to properly and uniformly grow.

Also, if you are gonna call it "the lasc oven trick", you should probably follow the instructions, as the LASC article clearly specifies 1 hour.


Pre-heat your oven to the pre-determined temperature (see chart) for the BHN you wish to achieve and then place the pan in the center of the oven for one hour. At the end of the hour as quickly as possible remove them and submerse in cool water http://www.lasc.us/HeatTreat.htm

that's my 2¢

[mehavey]

OKaaaaayyyyy.
We'll go 1-hr.

(Gawd, you guys give a tough drunk test)





Meanwhile, back at the ranch:

Last night's 459"/21-BN-at-the-surface bullets,
are measuring 14.9 just 0.17" in from that surface.

Film at Eleven.....

[mehavey]

OK. 90 minutes in a 480 oven for another 457183/#2, dumped in icewater.
(that way we have an average of 1 hour for the two bullets) [smilie=f:

We'll take a look Outside & In this evening.

[JonB_in_Glencoe]

Here is another thing to chew on.

some say, there is NO way to measure the BHN of the inside portion of a castboolit with the usual hobbiest tools.
Those that say that, will claim you are work softening the boolit by filing/cutting/sawing/slicing a boolit, no matter how careful you are. I will add that I highly regard the opinion of those that have told me this.

We all know, that Lee tells us to file a flat on a castboolit to measure the hardness with the Lee tool.
And that is exactly how I do it with small rifle boolits, like the 243 heat treated boolits that I tested/posted and linked to above...because there is NO other way (that I know of) to measure a small rifle boolit with the Lee tool.

I have also done some testing with 358 SWC boolits(two different alloys, some heat treated, some air cooled). In that test, I got the same BHN reading (or within one point), whether I used the unfiled flat nose or filed a flat on the side, like Lee instructs us to do.

Lastly, I will add that I am in the camp that thinks a boolit has the same hardness throughout the boolit, whether it's air cooled or WD or Heat treated (for a full 1 hour).

[mehavey]

That's why I'm using the 457193FN, because.... it's got a flat nose.:idea:
As to uniform hardening, we'll see. If the hardness changes as impressions are made from the side toward the center of a cut bullet, well, that pretty well cuts through (so to speak) the "cut bullet" problem.

Given heat transfer coefficient for lead is relatively low (of the metals), I just can't see the "instantaneous" chilling from surface-to-center that hardening depends on in big bullets -- but we'll see.....

[Tazza]

I was always under the assumption that COWW would water quench harden as there is arsenic in there that does the magical hardening. I thought the regular mix didn't really change much if at all.

The other thing is, will you loose any hardness post sizing? as it will press on the metal, possibly changing grains, but i would have thought that would be like forging, the more you squeeze it, the stronger it gets, to an extent.

The one odd thing i did find using "proper bullet alloy" i was being lazy to do a hardness test, rather than filing the top flat, i used a hammer to squash it down slightly to give me a flat nose, i got about 24-30BHN instead of the 15 or so it was meant to be. I got another projectile out of the same metal, filed the nose and i got the 15 i expected.

When talking to people at my local range, every so often the query the hardness of the projectiles i make, they aren't super hard, but we only use them in pistols for paper and steel. Some people seem to get too worked up about how hard they are, when it really doesn't matter for 99% of the targets they will be used on. Some feel if they are too soft they will lead the barrel up, i'm not sure how that could be, if the coating does it's job, there is no reason it would melt and stick. The hardness doesn't make it melt at a higher temperature.

One day i will test it, but i want to make some projectiles out of pure lead, coat them and see just how they perform out of my .38 super. If they fill the mould out correctly, i'd like to think they will shoot just fine.

The BHN debate is almost like asking what people the brand of oil they should use, everyone has their preference, and none are necessarily wrong.

[Whitespider]

I don't own any hardness testing equipment or tools, so this is just me thinking out loud (or with my fingers on a keyboard).

I'd like to see a test that concentrates more on the repeatability/reliability of the amateur ballistician grade equipment/tools that casters/reloaders typically use.
For example, boolits cast from 4 or 5 different alloys, each tested for hardness by 6-10 different people using their equipment/tools. Those doing the testing would not be told anything about the alloys, or the test results of anyone else until after all the numbers come in.

I'm always a bit skeptical of the BHN numbers being reported...
*

[JonB_in_Glencoe]

SNIP...

I'm always a bit skeptical of the BHN numbers being reported...
*
I am as well.

Here's my little story.
I bought the Lee tester about the same time I started casting, and BTW, I started casting cores for swaging and NOT for boolits. After reading a lot of stuff here as well as other sources, I had a theory about lead alloy and hardness...and how I could control the process for achieving a certain core hardness without risking damage to swage dies, and that is why I bought the Lee tool.

I'm not going to go into all details, but after a while, I learned that my technique using the Lee tool was flawed, as I was often (but not always) getting measurements that didn't come near what I was guesstimating. My issue had to do with using a dedicated press that happened to have some ram slop and me leaning on the handle in effort to make it easier to maintain pressure for 30 seconds. Now that sounds simple enough to troubleshoot, but it took me about a year to finally put two and two together to get 4. Obviously there are a number of flaws that could be incorporated into a persons technique with the Lee tool ...and other tools as well I suspect? but I haven't used any other tools.

[mehavey]

some ram slop and me leaning on the handle in effort to make it easier to maintain pressure for 30 seconds.How would ram slop/easy pressure make the 60# spring tension/indent-ball pressure (as measured by the indicator rod being flush) and less constant ?

https://s11.postimg.org/sllb5j2xf/BHN_Chart4.jpg

I've been running these numbers below over about a 10-year span of different RotoMetal shipments. They have been remarkably consistent/repeatable -- and the fact that I constantly get 14.9-15.0 for #2 over all those years says not much changes. (How can it? The indent ball doesn't change, the spring constant doesn't change, and the indicator rod length doesn't change.) (And BTW -- that pure lead number first showed up with some reactor bricks I'd had laying around for almost 50 years. But then Rotemetals never hit "5" either).

Personally, I like "soft". It covers a multitude of sins.
(And #2 w/ ALOX hits 1,850 in the BeoWooof all the time, and 2,100 in the `06 w/o a wimper)

I've been saying for many, many years that many of internet numbers for various/classic alloys are way high

[JonB_in_Glencoe]

How would ram slop/easy pressure make the 60# spring tension/indent-ball pressure (as measured by the indicator rod being flush) and less constant ?
If the ram is sloppy enough to move and the die doesn't, you end up with a oblong detent.

[mehavey]

-delete-

[mehavey]

To be honest, I've never encountered that. (Could happen though.)
The Celestron revealed remarkable roundness when used in my case.
https://thefiringline.com/forums/showpost.php?p=6103326&postcount=7

[Larry Gibson]

I too have been measuring BHN of cast bullets and alloys via various means for 40+ years. The most effective and consistent I've found is with the Lee BHN tool I've mounted in a microscope. I also take multiple readings (5 - 10) and average them out as taking just one reading on one bullet can be misleading.

I also am very leery of any BHN claim involving a decimal point. When anyone claims his bullets are 12.7 BHN it tells me he has not taken a sufficient sample amount. Now if he said his bullets BHN runs 12 - 13 +/- I'd be more inclined to agree. Note how the BHN scale is not linear. As the BHN increases the variance of indent size gets smaller; the indent size difference between a BHN of 10 and 11 is about .003. The difference of indent size from 26 to 27 is only about .001.

Once we get above a BHN of about 22 it becomes difficult to say for certainty, unless an appropriate sample is measured, what the BHN is EXACTLY......especially if a decimal point is used. Sometimes we get lost in minutia and don't see the forest for the trees..... Reminds me of a question I saw once; "If my range finder says the deer is at 270 yards but it's really at 273 yards how do I adjust my aim for that?"

As JonB mentions a loose sloppy ram can skew the indent size.....consistency is a must.

Larry Gibson

[JonB_in_Glencoe]

When anyone claims his bullets are 12.7 BHN it tells me he has not taken a sufficient sample amount.
I am guilty of posting beyond the decimal, but am only reporting what Lee's chart has listed, and I realize it's more of a range as you mention. Also, I tend to only do two samples for most batches of boolits...unless the two samples are different, then I'll do a couple more, then go from there, to find out why. That meets my simple needs.

The exception to that, is when I do more of an experiment like the two tests that I linked to in a earlier post. IIRC, I used 5 samples per batch.