I am planning to use an alloy for my cast bullets that I saw in an article by Glen Fryxell titled "A Few Comments on Cast Bullet Alloys." He states that if 8 lbs of Wheelweight alloy plus 2 lbs of pure lead plus "a couple ounces of tin" is combined it will yield an alloy that is 95% lead, 3% antimony, and 2% tin.

I want to add some lead shot to the mix to increase the arsenic content slightly; as I'm told this will help the alloy retain its BHN longer after heat treating in an oven.

My question is, how much of this stuff should I add to the mix described above? I know that wheelweights already have a small trace of arsenic in them, so I can't imagine that very much is needed.

Anybody's thoughts or opinions are welcome, :D

Thanks,

I am planning to use an alloy for my cast bullets that I saw in an article by Glen Fryxell titled "A Few Comments on Cast Bullet Alloys." He states that if 8 lbs of Wheelweight alloy plus 2 lbs of pure lead plus "a couple ounces of tin" is combined it will yield an alloy that is 95% lead, 3% antimony, and 2% tin.

I want to add some lead shot to the mix to increase the arsenic content slightly; as I'm told this will help the alloy retain its BHN longer after heat treating in an oven.

My question is, how much of this stuff should I add to the mix described above? I know that wheelweights already have a small trace of arsenic in them, so I can't imagine that very much is needed.

Anybody's thoughts or opinions are welcome, :D

Thanks,

Thing is Matt lead shot varies in arsenic content-- up to a max of around 1%. If you want to try boosting with lead shot I'd start with 10% of the content and test. Too much arsenic in an alloy causes other problems.

Storage in a food freezer likewise retards age softening.

Thanks for the advice Aladin. I did some number crunching today and it looks like the amount of chilled shot I am going to add will increase the arsenic content to no more than .21% of the total weight. That is assuming that the chilled shot has the maximum of 1% arsenic that you quoted. I believe that Marshall has recommended in the past to keep the arsenic at or below .25% of the total weight.

Somebody correct me if I'm wrong, but it looks like I should be all set with this amount.

Matt,

You should be fine with your target mix, as your arsenic indeed does need to stay under .25% of the total alloy composition. You are right that the presence of arsenic will indeed retard or even arrest age softening of alloys. However, I'll caution you, that even the best balanced of alloys (staying within the 5% antimony or under) for heat treating, while they will attain a maximum harness of about BHN 36 with oven heat treatment and quenching in ice water, will age soften, over the course of about three years max to a BHN 21-22, regardless of how they are stored, and what you do to them. This is why our bullets are a BHN 22 when we ship them, as they remain stabil at this harness nearly indefinitely. Should you work up a max, against the wall type cast bullet rifle load with a BHN 30+ heat-treated bullet, then put the ammo away for a couple of years before getting back to your pet project, you can have ammo that is WAY over acceptable pressure norms, because of the age-softening of your bullets. Just something to be aware of, and act accordingly. Above all, be safe!

God Bless,

Marshall-

Thanks for the advice. The Antimony content is going to be 3% so no worries there. Looks like the best thing to do is to heat treat for a BHN of 21-22 in the first place; that way there will be no surprises, right?

Take care and thanks again,