That was a guy I met one time. I would guess he was using regular 22 ammo but I can't say for sure.
But yes, you are 100% correct! Huge difference in sub vs super sonic.
This is where a lot of anti gun lawmakers want to say a suppressor is a silencer. They also want to lump it in with AR's.
Here is the full blown truth about the marriage of the two(suppressor and 5.56 ARs) If you take a 5.56/223 and load it down to
subsonic you have just created a 22LR with subsonic ammo. If you use normal super sonic ammo in a supressed 223 or a 308 AR
you still are gonna be really loud!!! It may not bust your ears to ringing with one shot, but your ears will still know it was almost painful.