Bullet Casting Question

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Hawkeye
Joined
Aug 16, 2005
Messages
7,054
Location
Milo Maine
Been reloading a while, now I'd like to cast some bullets. I've got a whole bunch of lead I believe it's pure no alloy in it. Most of it is chimney flashing and some plumbers lead. My question is What is the alloy one would use to harden it and second is at what ratio? Any help will be appreciated. Thanks ps
 

Cherokee

Single-Sixer
Joined
May 21, 2003
Messages
472
Location
Medina, Ohio, USA
Suggest you visit the cast bullets forum: http://castboolits.gunloads.com/

Tin was the one addition to harden pure lead in rations of 1 in 20 parts or 1 in 30 parts that was used for many years. However, antimony is better at hardening the alloy. If you can find them, wheel weights are the best source of a ready to use alloy and is frequently used as is @ 1/3/96. For most handgun use, 1-2% tin, 3% antimony (2/3/95) in your alloy will meet most neads. Hot high velocity loads will usually benefit from 5 or 6% antimony. Lots more info on the CB site.

Another alloy that you might be able to fine is linotype, as once used in the printing industry. it is 4/12/84 and when cut 50% with pure lead, will give you a 2/6/92 alloy for mag bullets. Cut it even more to get softer bullets for less than mag loads.
 

GP100man

Buckeye
Joined
Sep 13, 2006
Messages
1,386
Location
Tabor City, NC.
i use pure or stik on WW & clip on WW 50/50 & wind up with 11-13 bhn

i try for a little lower for wc boolits.

more than 2% tin is a waste of alloy , more tin will not harden lead any harder, gotta have some lino.
 

Rick Courtright

Hawkeye
Joined
Mar 10, 2002
Messages
7,897
Location
Redlands CA USA
GP100man":15lcep49 said:
more than 2% tin is a waste of alloy , more tin will not harden lead any harder, gotta have some lino.

Hi,

My understanding is the tin's job is to improve castability, and it doesn't get much better past that 2% figure. Antimony's the hardener... and what you're looking for in the linotype.

For a rundown of "common" commercial alloys, see www.rotometals.com and check their bullet alloys. They give approximate Brinnell (BHN) hardness numbers (their figures may be rather low compared to what the caster actually gets depending on how the alloy is further "hardened" after casting by water cooling, heat treating or both.)

Then somewhere floating around in casting info land, you'll find a number around 1422 which is supposedly a "magic" number. It's used in a formula that describes how hard you probably want your bullets to get best obturation, or "bumping up" (and theoretically, least leading?), based on the chamber pressures you're running.

It goes like this:

Hardness (BHN) = Chamber pressure/1422 or the converse, Chamber pressure = Hardness (BHN) x 1422. You'd use the first one if you know your chamber pressure and need to determine the required hardness. You'd use the second one to determine the max pressure you could run w/ a given hardness.

For example, let's say GP100man's just made a bunch of BHN 13 bullets and wants to know what he should load 'em in. 13 x1422 = 18,486. That tells us he's probably gonna have the best results w/ those bullets in loads running .38 Spl +P or lighter pressures.

OTOH, let's say I want to load fairly stout ammo for my .357 Mag, and know my pressure's gonna run about 30kpsi. 30000/1422 = 21.1, so I know I want my bullets running in the neighborhood of 20-22 BHN.

It's not a perfect system, but a reasonable working guide... YMMV, of course!

Rick C
 

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