Regarding the lead free aspect, I do not recommend using most momolithic bullets in a Chapuis, except for the North Fork Solids.

In the case of pigs I would use the cu point.

I had a conversation with the new owners of North Fork about the 9,3 and the Kalif lead ban and I suggested they make a Cup Point with a deeper hollow point, to make it an expanding bullet.

Even if they do not, you could deepen the Cup yourself and it should give more expansion.