BHN and accuracy

[BJung]

I read the thread Hardness Matters but didn't see my answer.

I cast my .38 and .45 acp bullets with the softest range lead available and save .40S&W bullets for the harder lead range lead among ingots I cast. Has anyone done a test comparing an accuracy load with different cast bullets with different BHN? How much variance would I expect before accuracy changes for the worse? I tend to let my ingots age and segregate them by hardness for different calibers. Can I get away with taking the large pieces of range scrap with some hardcast bullets added in, casting my TC 9mm and 40cal TC bullets and expect decent accuracy?

[BLAHUT]

I shoot pure lead in all my loads. Only shoot at a mild load. 45/70, 45/60 at 1200 FPS. Shoot faster need harder lead..

[megasupermagnum]

I have, but only in revolvers. The most recent I can recall was in 327 federal, comparing a 137gr SWC with water quenched range lead, to soft 20:1 alloy. I only fired 14 rounds of each, but I did not measure any difference in accuracy. The caveat is that particular load I've fine tuned. I've got the bullet size and lube dialed in just right. I've got the seating plug diameter dialed. I've got the powder dialed. I even twice tested a bunch of primers in that load and got that dialed. Also that was at 40 yards with wrist rested, not true bench rested shots. I was testing the soft alloy for hunting accuracy and was happy to find no loss. I even took it out a few days later and put one through a deer.

That's not a bad idea for a test though, I should stretch that out to 100 yards and do a proper benched 25 shot average of each.

[centershot]

BHN vs accuracy, is a hard bullet more accurate than a soft one? E. H. Harrison of the NRA thought so and stated such in the NRA's Cast Bullet Handbook. He said that the best target accuracy is achieved by using linotype alloy for target wadcutters. While I agree that lino makes wonderful WC's, today we know you don't need lino to make accurate target bullets. Or hunting bullets. The hardness of a cast bullet is only one factor in the search for an accurate load.

[Shopdog]

"The hardness of a cast bullet is only one factor.... snip"

Couldn't have said it any better. Generally,and this has to be well fleshed out... you want to go with the softest bullet that gets the job done. Just jumping into the deep end of hardness "can" cause more problems. Think of it like neck tension..... more isn't better,it's simply a test point. But,it's easier to compare one vs another. Alloy and any subsequent "hardening"....you need to figure out how to make your this vs that,more simple. If you have a low node acc load, "build" off that,adding a little toughness. You want to see where it breaks down,and stay just above that. Good luck with your project.

[deces]

The Lee reloading manual has many pages dedicated cast boolits, Lee clearly writes about measuring bhn for pressure limits for optimum accuracy in load development when used with their bhn tester.

[Larry Gibson]

The Lee reloading manual has many pages dedicated cast boolits, Lee clearly writes about measuring bhn for pressure limits for optimum accuracy in load development when used with their bhn tester.

Lee's formula uses a constant based on the plastic deformation of pure lead. If binary, ternary or quadra alloys are used then constant is wrong, and, thus, the conclusion based on the formula is wrong. This has been proven over and over again on this forum for many years now. Lee's formula is a dog that won't hunt.....

[popper]

Hardness doesn't matter, toughness does. Hardness is measured by a useable tool, toughness is more difficult to measure.

[405grain]

The advent of powder coating has really thrown a curve ball into the hardness/accuracy equation. With PC you can use a softer alloy, and the polymer jacket will take the rifling. Where this is most apparent is with hollow point pistol bullets. Softer alloy means better expansion, but to get that expansion you need speed. Normally using a really soft alloy at higher speeds isn't conductive to the best accuracy, but PC changed that. Just one more variable when thinking about BHN and it's effects on accuracy & performance.

[TurnipEaterDown]

Lee's formula uses a constant based on the plastic deformation of pure lead. If binary, ternary or quadra alloys are used then constant is wrong, and, thus, the conclusion based on the formula is wrong. This has been proven over and over again on this forum for many years now. Lee's formula is a dog that won't hunt.....

I have had a question on this for a while now.

I completely understand the statement made about there being an incorrect assumption on material properties in the LEE formula, and how this changes with alloy composition.

What I would like to understand is: (1) is the formula is valid for lead (having used properties for lead), and (2) if the correct material property values for alloy compositions were available (recognized: not easy w/ variable compositions), would the formula work when bullets were made of alloyed lead?

My thoughts always go to permanent distortion (bending) of the base from combustion pressure, and buckling of the column interior to the lube groove(s). The reduced OD "column" interior to the lube groove acts as a connecting rod between what is effectively a piston (base band) and the body, and would be susceptible to buckling. Granted that any potential for column buckling of this section interior to the lube groove has to be considered in light of the lube becoming pressurized in the groove and acting as support that would also resist the buckling (lube pressure being reduced as lube is stripped in the trip down the bore).

Distortion in either of these manners could easily lead to base perpendicularity issue(s) as the bullet leaves the muzzle, and therefore I think it is meaningful to understand the material properties and section attributes of the projectile in relation to chamber pressure.
For these reasons, I think it is important that bases be thick, lube grooves be shallow & placed as far forward as possible, if chamber pressure is to be increased as far as possible to gain performance.

[Tripplebeards]

I have done ladder tests on four different alloy hardness boolits in my Ruger 77/44 bolt action 44 mag rifle. All gas checked and powder coated. My best groups with 15.4 BH was at 1750 fps. My best groups from 7.5BH alloy came at 1600 fps. Didn’t really have a tight enough group with the two other alloys that shot under MOA so I don’t record them. I had to do some accuracy mods to get the best groups out of the rifle first. I had to bed the action, float the barrel, lighten the trigger, and add an a 14x optic that I wouldn’t normally hunt with. The scope has been changed out to a 3-9 since. My gun wasn’t shooting better than 2 MOA with my tighter load. The average was 4 to 6 MOA till I bedded it and floated the barrel. Then the same best grouping loads were shooting sub MOA. The worst groups were at largest 1.75 MOA. I also switched to a lee collet factory crimp which imo was the big answer. I never tried lighter loads in my 35 Rem 336 but can tell you 10.5 BH shoots in the same hole at 2100 fps. If I drop down to 7.5BH it opens up my groups to 2” at 100 yards. Without GCs I’m still experimenting…and trying not to get leading. The other two alloys l tried in my 77/44 were straight COWW and 50/50 pure and COWW mix. Neither shot MOA or better so I stayed with the two other alloys. Really didn’t make any sense to me at the time because it was my second try and gun loading for cast. But my alloy that was 7.5 bh shot best at 1600 fps and an alloy three times harder at 15.4 BH shot best at a 150 fps. Was using the Lyman devastator and H110 and lil gun powders. I know is if you switch alloy hardness in a given load the group size will definitely change.

[BJung]

It looks to me that the lower the bhn or softer the lead, the accuracy load requires a lower charge. Within the alloy, bhn is a combination of being malleable by using tin or hard by using antinomy. Then the caster can temper a bullet also. On threat I read by an African hunter was to find a load and then add lead until the group started to spread out. Thinking out-loud, maybe water drop such a bullet, de-temper the tip while the shank kept cold and gas check it. This is for a rifle bullet. Back to pistol bullets, I'll settle on the highest bhn from the same range scrap for the 40 and 9, and then load accordingly. I'll report on my findings at a later date.

[facetious]

Just for fun I cast a bunch of LBT OWC's from range scrap air cooling half and water dropping the other half. After more than enough time to age I loaded them both with my standard load. 15 gr's of 2400 and shot a 25 round group of each at 15 yd's.

The WD'ed ones gave a rounder and smaller group. WD'ed ones were more like AC'ed WW's.

[Larry Gibson]

I have had a question on this for a while now......................

What I would like to understand is: (1) is the formula is valid for lead (having used properties for lead), and (2) if the correct material property values for alloy compositions were available (recognized: not easy w/ variable compositions), would the formula work when bullets were made of alloyed lead?

My thoughts always go to permanent distortion (bending) of the base from combustion pressure, and buckling of the column interior to the lube groove(s). The reduced OD "column" interior to the lube groove acts as a connecting rod between what is effectively a piston (base band) and the body, and would be susceptible to buckling. Granted that any potential for column buckling of this section interior to the lube groove has to be considered in light of the lube becoming pressurized in the groove and acting as support that would also resist the buckling (lube pressure being reduced as lube is stripped in the trip down the bore).

Distortion in either of these manners could easily lead to base perpendicularity issue(s) as the bullet leaves the muzzle, and therefore I think it is meaningful to understand the material properties and section attributes of the projectile in relation to chamber pressure.
For these reasons, I think it is important that bases be thick, lube grooves be shallow & placed as far forward as possible, if chamber pressure is to be increased as far as possible to gain performance.

Not being a mathematician, it appears to me if the constant in Lee's formula is adjusted to represent the actual point of plastic deformation of the alloy being used then the results should be valid.

The problem with the OP's question, like so many we get on this forum, is there are so many other variables the questions really can't be answered.

The OP asks; "Has anyone done a test comparing an accuracy load with different cast bullets with different BHN?". Probably, but the results would only apply to that bullet, that load and that firearm.

"How much variance would I expect before accuracy changes for the worse?" Only the OP and his handguns and loads can answer that. Are we capable of accuracy testing with such handguns to actually see a subtle change in "accuracy"?

"I tend to let my ingots age and segregate them by hardness for different calibers. Can I get away with taking the large pieces of range scrap with some hardcast bullets added in, casting my TC 9mm and 40cal TC bullets and expect decent accuracy?" Is there really any way a reasonable guess can be made not knowing the alloy compositions of his "range scrap", the "hardcast" bullets or what his idea of "accuracy" is. Can he get away with it.....probably. Will it give decent accuracy.....again, only he can answer that.

Also as alluded too, BHN is only one half of the equation. Malleability is the other half [earlier referred to a "toughness"].

This is not intended, by any means to be critical of the OP and his questions. Just and simple explanation why his and many similar questions can't be truely given a hard and fast answer. There are just too many variables for a simple answer.

[blackthorn]

"I tend to let my ingots age and segregate them by hardness for different calibers. Can I get away with taking the large pieces of range scrap with some hardcast bullets added in, casting my TC 9mm and 40cal TC bullets and expect decent accuracy?" Is there really any way a reasonable guess can be made not knowing the alloy compositions of his "range scrap", the "hardcast" bullets or what his idea of "accuracy" is. Can he get away with it.....probably. Will it give decent accuracy.....again, only he can answer that.

Another question as an add-on to Larry's----"I tend to let my ingots age and segregate them by hardness for different calibers."---Is the OP aging the ingots to test and then picking which BHN to use? Or, does he expect the bullets cast to be the same BHN as the ingot? If the answer is yes to the second point, he is likely to be badly disappointed.

[Shopdog]

Just yappin;

For years now,have used torque wrenches in lieu of the factory handles on my 3 Lyman 450's. Actually,have used 3 different styles of them.... dial type,beam style,and then the clicker type. With truly custom reamed TP's that are much longer/supportive than either Lyman,or RCBS.

It has been an eye opener... the beam type wrench in use will; absolutely repeat on the #'s of when a batch is tested. The numbers mean nothing by themselves,.... meaning it's based on the leverage ratio that the 3/8" socket gets Tigged on the handle. Yes,you can still use the factory handle. Just sayin the #'s are going to be based on this "moment" arm.

But "laws have mercy" is it accurate for checking toughness/malleability from batch to batch. AND within a batch but there's not enough space to explain that one.....

Then,after that batches #'s are recorded and checked against previous,known values....well,we definitely ain't in Kansas anymore.

"Hardness".... on an upcoming piece of equipment,am going with a whole different approach. There's a name for the apparatus,which escapes me.... but it is used in industry for such tests. Basically twin vertical ground N polished rods. On it is a weighted carriage that gets pulled up,hooked to a cheap index style bow release aid. The bullet is in whatever you deem necessary... meaning the bullet doesn't have to just,"sit there". Like the TP's spoken of above.. in this application there's a socket for the bullet to sit in.... before the weight hits it. In this way,by altering the socket height,how much bullet is supported... you can test noses or bases.

So sorta,kinda;
Impact=hardness

Applied force(torque wrench)=toughness

[megasupermagnum]

The problem I have with the Lee formula is that it doesn't even seem close to reality. They came up with the formula by shooting bullets into a swimming pool and looking at them. I'm not sure what they saw, but it hasn't matched up to what I've seen. A good example is a soft alloy such as 20:1 is claimed to have a BHN of 10. I think it often tests a little lower, but we will say it is 10. According to the Lee formula, at about 12,500 psi we should start seeing deformed bullets with 20:1 alloy, which is just crazy. You will start to see your bullets deforming at a certain point, and I've seen it happen in the 30,000-40,000 psi range. By that I mean you will start to see you lube grooves start to collapse or bullet noes deform or "slump".

Here is the real issue with the formula, it depends on the bullet design. If you shoot a hardened steel screw at 10,000 psi, it will be deformed. It's all about support. Most bullet designs are designed to be supported as well as possible. On the other extreme is some bullet designs that are designed intentionally to deform. You can find a number of such with blackpowder guns such as a hollow based bullet, or even something like a TC Maxiball. Even more extreme is a hollow based shotgun slug. Look below at this slug on the right which was fired with a moderate load, probalby only 9,000-10,000 psi, maybe 1150 fps, nothing crazy. That was with an alloy about 13BHN, something Lee says will handle 16,588 psi. Sure looks heavily deformed to me (which is a good thing, that is why they shoot so good). The left slug is as-cast.

The Lee max pressure formula does not offer anything of value to the cast bullet shooter.

[BJung]

deleted

[BJung]

Just for fun I cast a bunch of LBT OWC's from range scrap air cooling half and water dropping the other half. After more than enough time to age I loaded them both with my standard load. 15 gr's of 2400 and shot a 25 round group of each at 15 yd's.

The WD'ed ones gave a rounder and smaller group. WD'ed ones were more like AC'ed WW's.

I am curious to know if the difference in groups was significant. What were they?

[BJung]

Yes, I let my ingots age and segregate them by hardness. I had a stack of ingots that were a year old were able to be scratched by an HB pencil and were among the hardest ingots I tested. They sat in my garage for a year and had tarnished. I used these to cast 40-170gr TC bullets and PCd them. They are being aged. By the end of next year (I have other tests to do) I'll shoot some of these and shoot some of these that are heated and water dropped. My target .38 and .45 bullets are made from cores with the jackets still intact. I am looking for a consistency in alloy composition. My worse range lead the small pieces left after the dirt and debri is removed. I make My brother makes fishing weights out of those. I was at first thinking that a certain bhn bullet made a more accurate bullet for a certain caliber. Now I am thinking that this can depend on charge weight.