Could you please provide some examples of ultrasonic cleaners "killing" most metals in silencers? Not trying to be argumentative, and I don't have a sonic cleaner myself, (I use a tumbler), but as far as I'm aware of, if the baffles are stainless steel, a sonic cleaner won't do any harm to the baffles. What you do have to be careful of however is the "finished metal" (basically your outter tube). I do have a buddy who uses a sonic cleaner on his .22 cans, and I haven't heard him say anything about killing the can. I did go the tumbler route, but before I bought one I did look at ultrasonic tumblers, and everything in my research didn't point to ultrasonic cleaners killing cans (again, it will kill the finish).
That said, now on my .22 cans, as long as I can get them open and knock off any chunks of carbon, I'm happy. IMO the baffles shouldn't be spotless anyways.
Just took my new 300 blackout AR off the back porch to see what she sounds like yesterday. At least to myself, my piston rifle sounds a lotter better than the DI AR using subsonic ammo.