I picked up a quantity of (I assume) reactor lead bricks. If they are pure lead great. But if they are the 4% Antimony then my question is if it is still a good choice for bullets vs lead/tin?

Thank you,
Charles

I am hoping it is the pure kind since a car key tip lightly pushed into a block left a small indent. Anyway, I will have it Assayed (someone here mentioned scrap yards have the tool) since it is over 400 2x4x4 blocks.

When I started casting decades ago I used alloys with antimony with the same Brinell hardness of 20:1 alloy made using linotype. 
It resulted in severe leading within 30 shots. 
On the advice of expert cast bullet shooters I switched to 20:1 lead:tin alloys and can easily shoot 100 shots without any leading.

Antimony and hard alloys appears to work well for hand guns.
However antimony also makes the alloy too hard resulting in a poor seal of the base when fired and results in gas cutting around the bullet. 
This results in barrel leading. Also the variation in gas pressures results in poorer accuracy in rifles.

With a 20:1 alloy you can easily shoot plain base grease groove bullets at 1850 fps (without a gas check) if you use a good quality lubricant.

However paper patched bullets are able to use the harder bullets since the paper creates the seal and the lead alloy does not touch the barrel.

I've mixed linotype into my pure lead for many years to cast bullets for all my rifles and handguns. It has 4% tin, and 12% antimony. I would think if it was going to harm my barrels, it would have done so by now. I see no issues, and accuracy is still great. I've heard people say antimony is bad, but haven't ever rear any scientific reason why?
I mix it 2 parts pure lead to 1 part linotype.

I've certainly cast and fired enough bullets with antimony in them to have no qualms about it.  Leading is more a matter of bullet fit than composition, IMHO.  

n.b. Maybe I am among the chosen few, but I've never leaded a rifle barrel.  So what do I know?

worse yet, it was an all or none, so there is also 60 (20lb) bags of shot which  I believe is pure lead because of the flat spots. Once I figure out what it is I will most likely sell some since I will never use it all. I just wanted some pure lead for paper patch, muzzle loading,  and paper cartridge projectiles. Plus for scheutzen and grease grooves to a known Pb/Sn since I have a supply of Tin.

Charles

Green_Frog wrote on Oct 3^rd, 2022 at 10:59am:


FROGGIE:

Charlie wanted to cast with a little antimony, a little tin, and even less arsenic, so as to have a heat-treatable alloy.  We discovered that this very "lean" alloy was leaving voids in the bullets.   He finally ended up swaging the bullets to form and heat-treating them to desired hardness.  Don't remember any other details.....guessing that was ~ 25 years ago.

The late Hank Stromberg was another experimenter.   Hank made a mould for a bullet with a square cross-section, so he could run samples thru the heat-treating process with his other bullets and measure the hardness on them directly.

CHRIS

I agree with Fred, have used a depleted Lino brew for all my cast shooting .22 to 30 cal. Have tested it at 20 bn,it’s slightly less than printing spec@ 22 bn mainly due to the Softer  spacers found in printers type. Only exception is my 40/65 RB ,I use 20/1. Never had a leading issue in any using the Lino ,always sized 1-2 thou. Over grouve dia.  Mal.