That copper slug should be OK and penetrate fairly well, but like Tom said, be of limited range due to it's poor weight VS diameter ratio. With a solid bullet, I'd like to see more frontal area for greater cavitation of soft tissue.

Drawing them down to groove diameter would be better than a thousandth over, if possible. If not, probably OK due to the deep hollow base.

With the rifled bores, filling the base cavity with lead would nicely heavy them up a bit & would probably make them more accurate due to stability. If they regulated well enough, they'd be good for way past 100yards.imho of course.