A 420gr, .50 cal, all copper bullet will likely penetrate very deeply as shown on their videos.
Lehigh load data suggests they'll be starting in the range of 1000-1400fps at chronograph distance.
Will it disrupt enough tissue for a quick kill on an Elk or Bear shot through the ribs?
I'd give Lehigh a call with a more specific question about that bullet for hunting to see what they recommend.
We'd love to hear what they say!