There's a couple places that make expanding projectiles for sub use. Outlaw State is one, Blackout Bullets is another. I have some of the BB, they expand well.

I personally would have no qualms about taking one of our small black tail deer with one. We brush hunt and most shots are 50 yards or less. I would wait for a good broadside and send it. I would not lob one out there at an unreasonable distance.

With respect to suppressed fire of supersonic's, it's awesome. My Harvester on my .308 or 30-06 sounds about like a .22 mag. I still use earplugs at the range but it's much more pleasant in the field. The recoil is knocked down to .22-250 levels also which is a nice benefit. The down sides are the extra length, POI shift between suppressor off and on, and significant heat buildup introducing mirage after 3-4 rounds.

All in all I love mine. It's beyond all comprehension why these things are NFA items other than Uncle Sugar wants your $200.