how to make an alloy to cast larger boolits? Add more antimony or more tin?

[bzajdek]

I have a mold that casts right under stated size and is not getting hit with my sizing die, actually a few molds that are on the border. I have wheel weight ingots, close to pure soft lead ingots, some range lead, and about five pounds of tin from pewter melted down. I also have a few pounds of brinnel 18 bullets from missouri bullet that i could use in an alloy and a little lead shot if needed. Would adding more antimony bring up bullet size, maybe adding more tin, or maybe going softer to cut the wheel weights down. I am more concerned with the size of the boolits than the boolit hardness right now(please no explicit joke references sorry don't know how to re-word that one) but I am just starting to learn. Any help is appreciated right now my alloy is around 1part wheel weights to 1 part range lead with about 1.5 percent tin. I also have 1 brass mold on the way and have read to keep the tin content low to prevent the mold from tinning. I have soldered before so i kind of understand that.

[jsizemore]

I've got a mold (my favorite) that casts on the small side. I use the same 50/50 + 2% pewter/tin. I found if you cast at a lower temp, then your boolits will shrink less. More tin will let you cast at a lower temp but too much tin will cause problems in the mold and barrel. Keep the antimony and tin balanced and the tinning problem ain't a problem. Since hardness isn't a concern, try Lyman #2 cast as a low temp as possible and see if you get some sizing.

If I cast at 650degF with my H&G 68 mold it will buy me 1/2 a thousandth with the 50/50 + 2%

[runfiverun]

That's lower mold temp combined with lower alloy temp.
Having said that if you look at straight Lino you'll only gain about .001 over ww alloy.
Now if you lap out the mold And add some antimony to your alloy you can gain .002 pretty easily.
tin is used to gain fill out, antimony for hardness.
There are other better way's to get what you want.

[MBTcustom]

I've got a mold (my favorite) that casts on the small side. I use the same 50/50 + 2% pewter/tin. I found if you cast at a lower temp, then your boolits will shrink less. More tin will let you cast at a lower temp but too much tin will cause problems in the mold and barrel. Keep the antimony and tin balanced and the tinning problem ain't a problem. Since hardness isn't a concern, try Lyman #2 cast as a low temp as possible and see if you get some sizing.

If I cast at 650degF with my H&G 68 mold it will buy me 1/2 a thousandth with the 50/50 + 2%

I do believe you've been to the circus and seen the lights!
That's exactly my experience.

[bzajdek]

ok, so i will lower casting and mold temperatures and hope i get good boolits, I was wondering why linotype will cast bigger? As i understand it linotype is about 90/5/5.

So I need to balance or have an equal amount of antimony and tin to make an alloy that will shrink less. In other words adding more antimony and keeping the tin percentage the same will not yield larger boolits or less boolit shrinking, Only harder boolits?

And adding more tin and keeping the antimony percentage the same will only help fill out of the mold until no more will be of help because the tin needs to bond with the antimony to create an alloy such as linotype?

[jsizemore]

Linotype is 4% tin and 12% antimony. Lyman/Ideal #2 is 90/5/5. You can keep your mold temp up by increasing your casting pace.


The tin helps with keeping your casting temp lower. The antimony adds structure, like steel in a skyscraper, to the boolit and binds with the tin so the combination of the 2 acts as one. The tin also helps the bond with the lead, call it the glue, that HELPS hold everything together BETTER and helps with fillout.

You do not need to balance the tin and antimony. It just makes it easier. Too much tin and it will look for something to stick to. Too much antimony and the casting temp goes up and the boolits become brittle.

The best way to learn is by doing. Keep records of your changes and if it doesn't work out you can remelt and try something else. There are any numbers of ways to get where you want to go. Learn them all so you can work with what you got.

[bzajdek]

Thanks I will experiment with them, I am also going to order some clover 320 grit valve grinding paste to open them up a little. I have used comet cleanser on a lee 6 cavity that did not like to drop bullets, they jump out now but it didn't increase the size at all. I think someone said it was equal to about 1200 grit and I have 2 steel molds that could use a little work.
thanks for your help jsizemore.

[Le Loup Solitaire]

Suggest doing a search for "Terracorp" formula. It used to be listed by Saeco and it gives tables with values for combinations of tin and antimony and the resulting effects on bullet diameters and hardness. LLS

[runfiverun]

Page 58 of the number 3 Lyman cast bullet book has one too as does the LAHSC site.

[bzajdek]

I have the 4th edition cast bullet handbook, so I will try the lahsc website. Does anyone think clover 320 grit is too aggressive to start with on steel molds,I would guess it is on aluminum but maybe not on steel.
thanks

[borg]

Remember, you can always take more off,, but you can't put it back on. I would go finer, JMPO