Silver shrinks a lot when cooled from molten state, but only 3% shouldn't shrink that much. Silver can be alloyed into a lead mix for bullets, there was a company a while back sold them. I can't remember their name. They advertised "The Silver Bullet", I think it was Lazer cast, but I heard they weren't putting it in on purpose, they were using an old Silver mine facility to melt their lead and silver was getting into their alloy as a contaminate, I can't prove that though,
Their was less than 1% Silver in their alloy.
Lead and Silver are found together in nature, typically Silver is a contaminate in lead and has to be separated out to get pure lead. In small amounts it will stay Eutectic.
In larger amounts it will separate out, I don't know what amount this is. I think in the phase diagram of lead, Eutectic is 97.5% pb and 2.5% AG so at least 2.5% of the Silver should stay in alloy at lead melting temps.
If it were mine I would alloy it into my lead, once small amounts of Silver are alloyed in to lead it will stay there, unlike tin that doesn't want to be there in the first place.
Larger amounts of Silver will not stay Eutectic and will separate out.
One thing small amounts of Silver will do is make the lead flow better in the mold but it will harden the alloy the same as Tin and Arsenic does.
Alloy it into the lead and don't worry about it. Just do it outside.
