20 lb. Pb with 0.5 lb. Pewter (ersatz 40:1)

[Hinnerk]

So I tested a couple of the .43 caliber bullets I cast up last weekend with my Lee lead hardness tester and found about 7.8 BHN (0.080" diameter impression). Sound about right? Lead was flea market mystery lead that tested at 5.0 BHN after casting into ingots. Pewter was mixture of scrounged material.

Sent from my E6810 using Tapatalk

[lightman]

It sounds like your flee market mystery metal was pure lead. Good catch!

[mehavey]

More like 20:1

241510

[richhodg66]

So, how does that alloy shoot?

[mehavey]

BTW: Modern Pewter ranges
94% tin, 1.0% copper, and 5.0% antimony
91% tin, 1.5% copper, and 7.5% antimony;

[Hinnerk]

So, how does that alloy shoot?Haven't tried it yet. It is for a .43 Spanish roller that I have yet to shoot.

Sent from my E6810 using Tapatalk

[Hinnerk]

BTW: Modern Pewter ranges
94% tin, 1.0% copper, and 5.0% antimony
91% tin, 1.5% copper, and 7.5% antimony;Is there a downside to using pewter? Will those small amounts of Cu and Sb have significant alloy effects?

Sent from my E6810 using Tapatalk

[mehavey]

It's the antimony which is kicking the hardness up a bit a la classic wheel weights
Wheel weights = 95.5% lead, 0.5% Tin, 4.0% Antimony

Should shoot fine at moderate pressures as-is.
Water quench will harden still further for higher pressure.

What are you planning to shoot them out of ?

[Wayne Smith]

As I understand it (not a specialist in metals) copper in small amounts refines the crystal formation and causes the alloy to be more flexible without breaking. In other words, a good thing for hunting.

[jsizemore]

40:1 is 2.5% pewter. Even at Mehavey's 91% Sn, 1.5%Cu, 7.5%Sb, your total % of Cu is .0357% and antimony is .1875%. Don't know how that makes it like COWW alloy. With so little Cu and Sb in the mix your hardness is coming from your Sn.

A 50's-60's NRA reloading publication lists 40:1 as 8.5 BHN

[mehavey]

Unfortunately (or fortunately), Sb hardens disproportionately to it's proportions (how do you like that for a little alliteration?) :kidding: so that said, internet lore continues to pass down BHN info that reflects alloys as being harder than they are.

The data in the chart below comes from actual Lee testing* of actual foundry alloys (e.g., RotoMetals) and pure reactor lead (my misspent youth) over several years. Reactor lead tests slightly softer than BH 5, and Rotometals lead/#2 establish the endpoints at exactly 5 & 15. Spring constants being what they are (constant), everything in-between is a smooth function of the math which is actually used to calculate the curve here), and quite predictable.

Tin makes things flow/fill out edges great . . . but doesn't harden things worth a darn. (note that 50-50 is barely BH 8.5)
But even small amounts of antimony (and arsenic) quickly have an effect.

241532

* Celestron digital microscope used to measure ball indent diameters here, but the old 2-glass/styrofoam Lee mount is surprising good too.
http://castboolits.gunloads.com/showthread.php?169268-Lee-hardness-tester-stand&p=1894714&viewfull=1#post1894714