I'm just starting to set up my new Bullberry 16.5" 25-45 barrel (Troy reworked the 25-45 Sharps reamer to make a tighter chamber and he's designated it 25-45 Bullberry). The barrel is threaded for a linear compensator so I can shoot it as a carbine with less muzzle blast. I realized that I can look at 25 ACP bullets and sub sonic loads and think about getting a supressor to thread on the barrel. For that matter, I could probably work up sub-sonic loads with heavier 25-35 bullets. :)
I'm pretty sure there's a fairly deep rabbit hole looming in my future.