The two non-toxic choices that can be used in shotguns and chokes designed for lead, that I am aware of, are Kent's Tungsten Matrix and Bismuth. Tungsten Matrix is a mixture of tungsten and polymer. Bismuth is soft and almost as dense as lead, I'm not sure about Tungsten Matrix's density, but is soft too. Do not get Tungsten Iron which is dense like lead and very hard, which makes it very effective when using modern guns. But it will wreck a fine double in a hurry. They are both pretty spendy.