Alloy and copper

[Griz44]

OK, I got a batch of lead that all indications show it needs some more tin in it to reduce surface tension enough to make the nice purty boolits I am used to seeing drop out of my molds. There is a mom and pop hardware store near the house, so I ran down there to grab some tin (in 95/5 solder form) Upon arriving, I discovered that they had none, but did have an Alpha metals product that is 95% tin, 1% silver and 4% copper. I shoot very soft alloy anyway, so the antimony (or lack thereof) is not an issue. The tin content is fine, the silver is a non-issue. What will the copper do to the castibility and subsequent hardness?

 

[zxcvbob]

Is that a type of pewter?

I suspect it will harden the alloy tremendously, like arsenic, calcium, or zinc, and *may* affect castability. Or the copper may be totally overwhelmed by the tin and not do much of anything (that's what you want)

Try a small batch before you mix up a whole bunch.

 

[243winxb]

http://castboolits.gunloads.com/ You may want to ask here. I would guess the copper would come to the surface when you flux. The melting temp of copper 1984, lead 621, tin 429, antimony 1166 would let you believe this is so??? BUT, I really dont know.

 

[RustyFN]

I was told by some people on Cast Boolits not to use that. I bought some 95/5 at Grainger that was 95% tin and 5% antimony.
Rusty

 

[243winxb]

http://castboolits.gunloads.com/showthread.php?t=18868&highlight=remove+copper i found this on a search. Looks like a lot of copper will plug the bottom pour pot. It can be diluted by mixing more tin lead alloy 50/50 to get better flow. Or possibly skim the copper from the surface by heating the alloy to around 500 degrees till it just becomes liquid, without fluxing. Skim off the lumps from the surface.

 

[Griz44]

Based on what I read on castboolits, I went ahead and cast tonight using the alloy made with the copper bearing tin. The casting went great. No problems. The finished product had a softer appearance, not like the bright silvery color of the first batch of material I had cast. Just for grins, I took a cooled boolit out to the shop and hammered it flat. I also took one from the first batch and did the same so I would have something to compare it to. It is a big more elastic, flattening more before coming apart. I think that is called ductility. I bet they shoot good!

 

[bullseye308]

http://www.thehighroad.org/showthread.php?t=366793
I just ordered some from him and the price can't be beat.

 

[243winxb]

If you add an Alpha metals product that is 95% tin, 1% silver and 4% copper to a 20lb pot of lead, the copper content will be .2% and the tin content will be 4.750% If i did the math correctly?? Do i get an A or F on math? lol

 

[Griz44]

I actually went a little lighter than that. I am shooting low velocity 45acp so I kept the tin at 3%. Yes, your math is good. I built a spreadsheet to do the calcs so I can input pounds added to the mix and get the rifgt amount of tin.

 

[RustyFN]

Griz I was wondering how much solder you add to your pot? I bought some 95/5 solder to add the other day and haven't had a chance to cast any more yet.
Rusty

 

[zxcvbob]

...copper content will be .002%

.2%, not .002%