How do you determine lead alloy hardness?

[314159]

I don't have a way to determine the Brinnel number of a lead. Actually, I had to look it up to be sure I spelled Brinnel properly.

When a bullet is advertised as "hard cast" is there a simple way to determine if it is? Even if it was only a way to compare one against another, that would be useful.

[whomever]

Doing it accurately is going to require a Brinell tester, which isn't cheap. The basic principle is to put a small hard ball on the material, apply a certain amount of force, and measure the resulting indentation:

https://en.wikipedia.org/wiki/Brinell_scale

For a DIY rough comparison, your problem would be to measure the indentation accurately (or, alternatively, the amount the penetrator moves - that's how Rockwell testing works).

You might try, say, applying a known weight to a center punch and comparing the resulting divots on known and unknown hardness samples.

If you can find a weight and penetrator combo that gives you differences you can see with a loupe, it might work ... or not, never tried :-(


There are commercial testers made for lead testing; I have no idea how well they work:

https://www.amazon.com/LEE-PRECISION.../dp/B004Y6YH3W
https://www.buffaloarms.com/lead-har...ard-ctlt1.html
https://www.midwayusa.com/product/10...18/?pid=193445

[the Schwartz]

I don't have a way to determine the Brinnel number of a lead. Actually, I had to look it up to be sure I spelled Brinnel properly.

When a bullet is advertised as "hard cast" is there a simple way to determine if it is? Even if it was only a way to compare one against another, that would be useful.

Fear not.

There's a simple test that used to be—and might still be—an ASTM approved method to determine the hardness of lead-based alloys.

Using the following hardness equivalence chart, it is possible to obtain an approximate Brinell hardness number using draft pencils of varying hardness (6B through 2H) as below:

6B 4-5 BHN (pure lead)
5B 7-8 BHN (40:1 lead-tin alloy)
4B 9 BHN (25:1 lead-tin alloy)
3B 10 BHN (20:1 lead-tin alloy)
2B 11-12 BHN (10:1 lead-tin alloy)
B 13 BHN
HB 14-15 BHN (1:1 lead-linotype alloy)
F(#2) 16-18 BHN (quenched Lyman #2 alloy)
H 20-22 BHN
2H 26-28 BHN (monotype alloy)

Using a freshly sharpened pencil, apply pressure at approximately 45° incident to the alloy surface and push the pencil tip forward.

A pencil that scratches/marks the surface of the alloy is as hard as—or harder than—the alloy.

A pencil that does not scratch/mark the surface of the alloy is softer than the alloy.

Using this technique, you can bracket your alloy's hardness and get a fairly close approximation of its Brinell hardness number.

Good luck.

[314159]

The Schwartz is "The Man". I could not have imagined so simple a test existed. Thanks.

[Malamute]

Can I ask why you want to determine the hardness? Im curious.

The term "hard cast" seems to have become somewhat of a catch phrase in the shooting world and marketing of cast bullets. Its often implied that the harder the better for various reasons, though also implying its best for everything to be "hardcast". Leading the bore being one reason, and shooting large animals another. The hardness is often overdone for no particular good reason, its just marketing. The lube is more important than the hardness as regards barrel leading. Super hard cast bullets also can be more brittle causing breakup. Linebaugh commented often about bullets being too hard for best application in large game applications such as his large caliber pistols were sometimes used for.

Bullet makers should be able to provide exact hardness or alloy composition if asked.

The lube used in most commercially available cast bullets isnt as good as it could be, its more oriented to not getting the bullets sticky when handled. Leading problems can often be corrcted by removing the hard lube and using a better grade lube, though that adds steps. Some makers will use a different lube when requested, like Javelina, SPG, or others. Another Linebauh pet peeve, he called most bullets lubes crayons.

[willie]

The consensus among experienced cast bullet shooting is that bullet hardness should match velocity range. For example, standard velocity loads in traditional calibers like the various 38's, 44 Spl, 45 ACP, and 45 Colt will show better accuracy and almost no leading or zero leading when cast of softer alloy. What is that? Lead harvested from ranges. Wheelweight lead works nicely and even can be made less hard with scrap lead added. Adding tin will assure that bullets fill out nicely.

I've studied casting in a scholarly manner for over 5O years and observed much misinformation. Note that above I suggested using scrap lead and adding tin which can be found in linotype or pewter or solder. In other words, make up a large batch of clean alloy and work with it. Add a smidgen of tin to the pot. You will make good bullets. Use a recommended lube mentioned by the o.p. Or buy Lee Alox, cut it with mineral spirits, and tumble lube the bullets.


I used the term scholarly but spared the reader technical jargon. Just start casting. Lee makes a lead hardness tester.

[Malamute]

Willie makes a good point, hardness in cast bullets becomes more of an issue when approaching rifle velocities, the Lyman manual shows many cast rifle loads in the 2200 fps range. At pistol velocity its less of an issue how hard they are.

Before there was much commercial cast bullets easily available I cast with straight wheel weights for 44 magnum loads, 22 grs 2400 with the Lyman 429421 mold with old school Lyman Alox lube (not exactly the same as the current Lee liquid alox stuff). No leading issues in a 4" Smith 29. I also cast for 45-70 400 gr bullets with both black powder and smokeless with no leading issues. Either would have been operating in the 1200-1300 fps velocity range. I used both the old Lyman Ideal lube and Alox with the 45-70 bullets. The black colored Ideal lube was supposed to be suitable for either black or smokeless powder loads. Both were somewhat gooey in consistency and the bullet nosed needed to be wiped clean after loading to keep things clean and not attract dirt. They seemed to lube well though.

Increasing velocity over that range will probably require somewhat harder bullets, but I dont know where the velocity level is, it may be different for various guns and lube used.

[314159]

My curiosity was piqued by Buffalo Bore .32 SWL WC ammo using the term in their ad copy. Thought I might compare it to some Fiocchi WC ammo I had on hand. Then check out some Federal 148 WC, etc...

I haven't been a reloader in a long time and I never cast my own, even then.

[358156hp]

Bullets made "hard cast" are simply made from an alloy rather than pure lead. Most commonly, pure lead is alloyed with a portion of pure tin and the resulting alloy will be harder than pure lead, which is where the term comes from. Notice I said "proportions". Lead/tin alloys are identified by their ratios, most common of these are 40:1 (40 parts of lead to 1 part tin), 30:1 (30 parts of lead to 1 part tin), 20:1 (20 parts of lead to 1 part tin), 16:1 (sixteen parts of lead to 1 part of tin), and the dark horse is 10:1 (ten parts of lead to 1 part of tin). Bhn numbers are as follows: 40:1- bhn 8, 30:1- bhn 9, 20:1- bhn 10, 16:1- 11 bhn, 10:1- bhn 12. These numbers are from my copy of the original lead alloy calculator and I'm certain somebody will join in with different numbers shortly.

Additionally, some people also add antimony to harder bullet lead even further. These mixes are identified by percentages of each element. Thing start getting really confusing at this point, while everything is on the up and up, results will often get skewed when salvage elements are used. The prime example is any salvage lead that has been swaged. Almost all swaged lead products contain a few percent of antimony as a grain refiner. Pure lead only swages okay, but when you're making lead sheathing, lead pipes, and that sort of thing you need everything to be perfect so your customers don't get mad at you for misshapen parts and a bit of antimony can help you immensely with your quality and the resulting customer satisfaction. You won't be looking at sometime down the road at how that little dab of antimony might throw somebodys alloy calculations off in the secondary salvage market. So now if we look at the popular 90-5-5 bullet alloy (90% lead, 5 percent antimony, and 5 percent tin) we'll expect a resulting bhn of approximately 16. 90-5-5 alloy is also known as Lyman #2 alloy.

I don't have direct information on which alloy is most commonly used for factory hollowpoint bullets, but the general consensus is that it's 30:1. Depending on caliber and velocity I cast my own hollowpoints with either 20:1 or 30:1. Elmer Keith has written of using 16:1 for hollowpoints in the olden days. Cast hollowpoints and jacketed hollowpoints are totally different on all levels so 16:1 may be more similar in performance to JHP. The only way to know is to use due diligence and do your own performance testing. One reason for antimonial alloys being so popular is the cost of pure tin, which runs over $20.00/lb for foundry sourced tin. Salvaged pewter is a less expensive option and generally runs around $10.00/lb plus shipping. I won't go into heat-treating cast bullets. Many bullet casters have inexpensive version of bhn testers, but these testers cannot tell you the composition of your alloy, only the hardness.

[Malamute]

My curiosity was piqued by Buffalo Bore .32 SWL WC ammo using the term in their ad copy. Thought I might compare it to some Fiocchi WC ammo I had on hand. Then check out some Federal 148 WC, etc...

I haven't been a reloader in a long time and I never cast my own, even then.

As a generalization almost any cast bullet will be harder than almost any swaged or factory wadcutter bullets. Swaged are cold formed under pressure, not melted and cast in a mold. Hard cast can mean almost anything the person stating it wants it to, somewhat like "mil-spec" in AR parts can mean almost anything the advertiser wants it to, whether it truly meets full specifications or not, theres no actual standard per se in advertising, only in .gov acceptance specs, which most parts makers dont have to meet.

...well reasoned and insightful post.....

Good post!


Most of us old school cheapskates used wheel weights because they were free back in the day (most tire shops would give you a 5 gallon bucket or two just for asking, at around 150 lbs per bucket) and made of reasonably hard alloy for most uses. For higher velocity rifle loads adding a bit of other elements as mentioned can up the hardness of wheel weight metal, but it covered quite a lot of shooting needs as is. Sadly, the composition of wheel weights has changed to zinc and steel weights, and they often charge for buckets of them or at scrap yards they are charging more now. Supply and demand. Lead is being phased out in some uses.

Ive used recovered bullets from backstops, jacketed bullet cores seem pretty soft compared to wheel weights. Its weird to melt the weights and bullet scraps and have the metal clips and jackets float to the top of the molten lead. Its pretty interesting to cast bullets and allows you to make about any bullet style or type you care to buy or borrow a mold for. The castboolit forum is one I can easily get sidetracked on for quite some time, and its often the place with the most load info for any cast loads you can think of, obscure rounds or hair brained ideas. In the early 80s there werent many cast bullet suppliers, you had to cast your own if you wanted to shoot much on a budget or get anything the least bit out of the norm. Most commercial lead bullets from larger bullet makers were soft swaged and often leaded barrels pretty badly at anything above low target velocities, they werent suitable for magnum velocity loads. Casting your own cured that issue.