As much as I agree with this, I feel that it will not go through (PLEASE let me be wrong).
In urban areas, great expense has been made for systems that can triangulate the report from gunshots. The systems can differentiate between backfiring motorcycles and different types of firearms. I assume between pistol and rifle. They are pinpoint accurate as all heck, too.
With systems like this in place, I doubt there would be much foothold for this Act.
However.... I would welcome the ability to shoot suppressed subsonic 9mm.
EDIT..... Took Action.