You say you lost 3 deer with shoulder hits and a 250 gr shockwave with 100 gr Pyrodex?

It sounds like the bullets were not penetrating, and to me that means they were coming apart, not failing to penetrate because of a lack of powder. But, I have not heard that the SWs come apart. So it is strange to me.

Give FPBs a try. They will penetrate and give you two holes. Better for tracking on a marginal hit, and if you hit the shoulders, the deer should not go even a 100 yds, let alone 2 miles.