BHN and accuracy

[burbank.jung]

Has anyone conducted a test comparing their accuracy load and BHN variance? I tend to save my softest alloys for .38 and .45 and then save the hardest alloy for my .40 S&W. Can I use the same ingot hardness for 9mm or is that too hard? I segregate my ingot range from range scrap source. Once source is jacketed bullets. Another is separated lead from jackets and hardcast. And last, lead remaining after the dirt and wood debri was removed. The last tends to be the hardest.

 

[Brad]

Way to many variables here.
Accuracy at what velocity? Handgun or rifle?
I know Rick did some testing years back on BHN and accuracy with his silhouette revolver. Not sure if he tested accuracy with varying BHN in a group- Rick doesn't do varying BHN in a group.
Realize that Rick is a game fine revolver shooter and has a very accurate revolver.
I don’t think a 3-5 BHN variance in a handgun fired at 10-25 yards will matter.

 

[burbank.jung]

Handgun. Thanks.

 

[Rick]

Has anyone conducted a test comparing their accuracy load and BHN variance? I tend to save my softest alloys for .38 and .45 and then save the hardest alloy for my .40 S&W. Can I use the same ingot hardness for 9mm or is that too hard? I segregate my ingot range from range scrap source. Once source is jacketed bullets. Another is separated lead from jackets and hardcast. And last, lead remaining after the dirt and wood debri was removed. The last tends to be the hardest.

Heat treating cast bullets and lead - antimony - arsenic alloys

From this article . . .

I did an extensive BHN test in my 9" Freedom Arms Model 83 357 Mag revolver that took over a year and a half and fired hundreds of rounds in five shot groups. Using only virgin WW brass and all powder and primers from the same lot number and all alloy from the same lot, I fired 5 shot groups at 150 meters scoped from the bench (12x Burris). All bullets were sized nose first in a Star Lubrisizer and lubed with LBT Blue. All loads were as identical as I could make them changing only the bullets BHN by heat treating. Best grouping and highest velocity was with bullets at 17-18 BHN. Testing started at 11 BHN with air cooled wheel weight + 3% tin, various BHN's were tested up to 30 BHN. Harder than 17-18 cost velocity plus groups opened up, softer than 17-18 and groups opened up. None of the loads caused any leading in the FA but proper bullet fit is as or more important than alloy BHN. This revolver likes it's near max load with 18 BHN bullets. Consider the best groups and highest velocity with 18 BHN bullets and compare this to the 20 to 24 BHN of many commercial cast bullets. 1440 x 18 BHN and a minimum pressure of 26,000 PSI is needed. This very near max 357 Mag load (9" barrel, 190 gr. bullet @ 1550 fps) is about 9,000 PSI over the minimum 26,000 PSI for 18 BHN and is where it shoots it's best with zero leading. This does not mean that you must be as much as 9,000 PSI over minimum BHN but this revolver with this bullet/load likes it.

An interesting side note of this testing was mixing different BHN bullets within the same 5 shot group. Using a BHN range such as 17-18 or 15-16 didn't effect groups but the worst groups fired throughout the tests were with a wider variation in the BHN. When groups were fired with BHN ranges such as 15-20 BHN or 18 to 25 BHN bullets wouldn't even stay on the 150 meter target much less group. BHN variation opens up groups and the more variation in BHN the larger the groups.

 

[fiver]

and then he didn't screw it all up using neck tensions all over the map either.


i use pretty much 2 alloys.
the regular one and the regular one water dropped.


i have another one but rarely use it.
it has it's advantages and it's drawbacks, it's mostly saved for certain bullet designs and velocity windows.

there's no reason to make this stuff hard.
make some bullets.
start low and work your way up.

 

[Bret4207]

What Fiver said. You asked this question before, several times IIRC. Read Ricks post. That tells you what one gun using near max loads liked. That doesn't mean the same gun using milder loads is automatically going to want the same Bhn for best shooting. IOW- when shooting a near max load with that bullet in that gun the bullets Dynamic Fit was best balanced at the higher Bhn. That doesn't mean it works that way across the board with other guns/bullets/loads. It might, but it might not. You keep looking to a magic answer that centers on Bhn. Sorry man, that isn't the One True Answer! All the other variables add up to give you the final result. Try thinking in terms of finding the best fit, not the best Bhn. They aren't necessarily going to be the same thing, Bhn is just a part of getting the best fit.

Follow Fivers advice in post #5.

 

[Ian]

I feel trolled. We've been through this over and over, obviously to no effect.

 

[Dimner]

BHN testing is my absolute least favorite thing to do with reloading. I'd rather clean out my lead melting pot or fireform brass. Or watch reality tv (I'm trying to come up with the least fun activities.)

I only own a BHN tester to see what my alloy hardness is and to see how my PC technique changes that alloy hardness. I don't care what the BHN is. I just want to know how it changes in relation to the PC technique. I have two techniques. 1) Normal 2) A bit harder

I have never gotten to a point in load dev where I have needed to change BHN. Ever.

 

[Snakeoil]

No expert here by a long shot. But I think a key point made in that article excerpt was hardness will alter pressures and probably the shape of the pressure curve. That is why mixing them opened up the groups. It would be like having neck tension all over the place or the crimp being different for each round.

If you only have one gun, you probably will have the time to run thru all the variables and combinations of variables to figure out the optimum cartridge parameters necessary to squeeze the best accuracy and consistency out of that particular firearm. But if you shoot many guns, unless you have no life and nothing else tugging at your time, I doubt that you'll ever have time to figure it out for each gun and still have time left over to actually enjoy the fruits of your labor.

 

[popper]

Cast some 9mm from your 40sw alloy. Wait a couple weeks, then dummy load the 9mm. Pull the bullets and check base for undersized. If so, you need harder alloy. 9mm case has tapered walls, alloy must be hard enough to NOT get sized down base. If the alloy is too hard, 9mm pressure isn't high enough to bump up the base size. Then you get gas cutting of the base. 40 doesn't have that problem. 9mm pistols ae also notorious for the sharp edge entering the bore - another problem. 3rd problem is many use RN bullets and seater stem MUST be matched to the nose or the bullet gets seated slightly crooked. 9mm is easy to reload but hard to reload well.

 

[Joshua]

If I can hit clay pigeons at 25 yards most of the time with my .357 I’m happy.

Basically I started out casting with a bunch of unknown trash fishing weights. I was able to get “minute of clay pigeon angle” with those loads.

I acquired some “known alloy”, well actually just a batch of CWW. I was also able to attain that same level of accuracy!

I bought a set of pencils. And started checking for relative harness.

I’ve cast batches of range scrap, fishing weights, clip on wheel weights, boat ballast mixed with pewter, and pure roof flashing mixed with pewter.

For me with my level of desired pistol accuracy, BHN just doesn’t matter. All the above have shot to my desired plinking accuracy.

With higher velocity rifle bullets I have powder coated some of the harder alloys listed above, and I have also hardened those alloys up with the addition of Linotype.

With these higher velocity powder coated rifle loads I have found that the single most important factor related to accuracy was not BHN or type of alloy used. It was the design of the bullet. Some shapes in some barrels can be pushed faster than others. These bullets just needed a bit of hardness but not too much.

In low node rifle loads I use the same soft to medium stuff that I use in pistols. Tumble lube, and find a load that is acute.

I’m positive that I could squeeze out more accuracy. Ten shot groups 2” to 3” at 100 yards with my rifle loads is acceptable to me. Clay pigeon accuracy at 25 yards with my “target revolver” is acceptable to me. Fun/hunting accuracy is all I need from my cast loads right now.

If I was competing that level of accuracy would not be acceptable. I’d dig deeper.

What I get out of Rick’s writing is that consistency is really the key. I keep all my bullets grouped in batches. I try very hard to keep my alloy consistent when adding alloy to a pot while casting.

I see the utility of having only one alloy. My next evolution may be to make up a very large batch of a homogenous alloy. With a reserve of pure for black powder use.

 

[Bret4207]

I feel trolled. We've been through this over and over, obviously to no effect.

Maybe we should establish a "Beating a Dead Horse Award"?

 

[Rick]

Maybe we should establish a "Beating a Dead Horse Award"?

Yep, I'm about done with the same question asked in different ways. And still, he is not getting the answer he wants so he comes up with new ways to ask the same thing.

 

[fiver]

well i guess we could just say 1422* BHN ='s your perfect pressure window.
it works.
it's wrong,,, but it works.

 

[Rick]

I think what's wrong with that formula is that people think it's gospel, it's not. It can be a guide, one more tool in the drawer but don't bet the farm on it. Just one more thing to look at is all.

 

[burbank.jung]

I once found a table listing the best bhn for 40 cal is between 18-20. Then another person says 12. My hardest ingots is somewhere around 14-15bhn. Just as I'm discovering that bullet seating affects pressure just as powder quantity also could affect pressure and as a result accuracy, I am thinking that BHN and accuracy depends on the load. So maybe a high bhn would work for a hot load while a softer bhn would be just as accurate with a lower charge. Therefore, bhn doesn't matter as long as I have the right load for that bullet. Am I on the right track here?

 

[fiver]

not BHN but what is actually in the alloy.

i worked with Popper a while back on an alloy that contains Zinc, copper, and Tin.
the key was to add in just a little bit of antimony, this 1% addition to an alloy containing 1% Zinc less than 1/2% copper and AIRC around 1/2% tin.
how hard can Lead be with about 3% of anything added in?
hard enough for full velocity 35+K loads without a gas check.

the other part of the puzzle is in how hard are you hitting the bullet.
smacking it with a golf club is gonna require the bullet has some structure to it so it doesn't reshape itself into a wad cutter.
flinging it from a sling is a lot gentler.
hitting it with a tennis racquet is kind of in the middle.
bashing it with a hammer is gonna make whatever alloy you got mush down, or if it's nice and hard it'll just break into some little pieces.

i don't cut lino-type i break it.
if you want high BHN and hardness go ahead and break your junk and ruin your throat.

antimonial dendrites are like little hooks, they scrape at stuff as they move over it,lead, copper, steel, whatever.

 

[Bret4207]

I once found a table listing the best bhn for 40 cal is between 18-20. Then another person says 12. My hardest ingots is somewhere around 14-15bhn. Just as I'm discovering that bullet seating affects pressure just as powder quantity also could affect pressure and as a result accuracy, I am thinking that BHN and accuracy depends on the load. So maybe a high bhn would work for a hot load while a softer bhn would be just as accurate with a lower charge. Therefore, bhn doesn't matter as long as I have the right load for that bullet. Am I on the right track here?

You are sort of getting there...finally. What you seek is balance that allows the best fit. Common lead alloys Bhn doesn't matter like you want it to in the grand scheme of normal 650-1800, maybe 2200 fps, be it handgun or rifle, those common alloys running from maybe 11-18 Bhn. But it's going to depend on a lot of other variables that affect FIT. FIT is what matters! Told you that 7 ways from Sunday over and over again. Bhn is NOT the deciding factor you are trying, desperately and repeatedly, to make it out to be. Oh yeah, and Bhn CHANGES over time, so your super HARDCAST bullet is going to soften. Surprise! And Bhn in an ingot is going to be different thatn Bhn in a bullet. And Bhn is not an indicator of what the alloy is made up of, which is more important than Bhn. Like I told you months and months ago, I wish it were that easy, but it's not. Forget Bhn, mix up a big batch of alloy, cast up as perfect bullets as you can and go shoot them. See what the gun says and work on the other 100 variables that make it shoot good or bad, but forget Bhn for now.

I hereby nominate myself for the "Beating a Dead Horse Award" for giving the same info to the same guy asking the same question for the umpteenth time...

 

[Ian]

well i guess we could just say 1422* BHN ='s your perfect pressure window.
it works.
it's wrong,,, but it works.

You forgot the minus 10% part. It also works out to 120-140K RPM much of the time for stuff under 35 caliber. Those guys must be geniuses...

Funny thing about soft alloy with some resiliency engineered into it: the more it yields to engraving, the less it resists it and the less pressure builds behind it in the throat, the less it wears stuff out, the better it obturates (seals up) the bore, the farther down the barrel is the pressure peak, and the faster you can push it without making it into a wadcutter or lump of putty. If you don't want to screw up your bullet's shape when firing it, don't make it out of super hard brittle unyielding stuff and don't shape it to perfectly match the throat and don't park it so hard into the ball seat that it takes 30K psi just to get it moving out of the case neck.

 

[fiver]

chuckle... unless you need to do that stuff to make the powder work..

Funny thing about soft alloy with some resiliency engineered into it: the more it yields to engraving, the less it resists it and the less pressure builds behind it in the throat,

kind of the recipe for powder coat,, ya know.