SAC silver solder question

[John in WI]

I was reading on another casting/reloading page last night that copper can be used to "toughen" a boolit alloy. As opposed to antimony that is used to harden it.

I have a big spool of Bernzomatic SAC800 (SAC=Sn Ag Cu) lead free silver bearing solder and was wondering if I could get some assistance.

early in the summer I casted some split tips for my .38 out of dead soft, and dead soft with a touch of tin in them. Both expanded 100% of the time, but they nearly always lost part or all of the tip. It didn't look to be snapped off (from the lead being brittle). It looked more like the tip was so stretched back that it eventually failed.

I'm wondering if a touch of copper in the alloy could help hold the tip together? Expansion with these things doesn't seem to be a problem. I think because there's no hollow point to get clogged up. The object you're shooting at must really wedge the tip open.

[bumpo628]

The composition of that solder is approx:
<1% Silver
3-4% Copper
95-96% Tin
http://www.worthingtoncylinders.com/Libraries/MSDS_Sheets/Eng-Lead-Free-Rosin-Core-Solder-MSDS-6-11-11.sflb.ashx

However, with the small amount of solder that you will add to your alloy the final copper % will be very low.

For example,
1 lb of SAC solder + 19 lbs pure lead = alloy with 4.75% tin, 0.20% Copper, 0.05% Silver, 95% lead
(assuming 4% Cu) That is a bit more than a touch of tin and the Cu content is still pretty low.

Ultimately, you going to have to try it out and see how it works.
I'm sure that having the copper and silver in there can only help your situation.

[John in WI]

I'm really flying blind here, but I made a batch of boolits with 1:1 lead to soft range scrap and about 2% added tin.

Then I made another batch with 1:1 lead to scrap and a good about 4% additional tin (added in the form of silver solder).

I think this is going to be a matter of tuning the lead hardness to the speed. But it would be nice if I could strengthen the alloy without really hardening it! Maybe a touch of copper would be enough to help me out with that.

The only way to know is to do some blasting with them I guess.

[lwknight]

303 guy did some work on using copper in his alloy. He had good results too. IIRCC the copper was limited to 1% or so and the tin was higher.

Tin loves copper and makes a permanent bond at the molecular level. You can actually dissolve copper in a tin/lead alloy if you have enough tin but the copper dissolution percentage is very limited and still makes profound differences.

My personal experience is that higher tin without copper is the ticket to weight retention.

Keep us posted on the results.

[John in WI]

Thanks for the info. I loaded some dead soft, some soft with 3% tin, and some soft range scrap with 2% tin added in the form of silver solder (so it contains a bit of silver and some copper).

I'm hoping to run them through some redneck ballistics and see how they do against water jugs (those are pretty violent for exansion) and wet pack phone books. Unfortunately I got rained out this weekend so hopefully next weekend.