Current just for fun project

[detoff]

I'm working on a solution for a problem that doesn't exist... For the hell of it I currently have a Thompson Contender 7mm TCU barrel off for threading so I can shoot it suppressed (Hell I may even make the pistol into an SBR). I'm wondering if there is a .284 bullet that will expand at subsonic velocites? I think I can get the 150 gr class subsonic using Trail Boss, and am thinking of the 154 SST's. Use will be just for fun and maybe small game/varmints. I've shot deer with the pistol in the past, but not interested in subsonic loads for that. I've already got a 300 blackout so that realm is covered. I have everything from 110 TNTs to 185 RDF's. However, being a 1:9 twist, I'm hesitant to use bullets over 160ish since I don't want to enlarge the holes in my suppressor baffles inadvertantly. I'm open to any thoughts, like I said, this is for fun and the hell of it. It'll fill the spot between my suppressed 22 pistol and 300 blackout.