03-01-2018, 05:02 AM
Haven't heard a grendel, but a 223 suppressed is not much louder than a 22lr rifle unsuppressed. 308 is pretty similar. The loudest part is the supersonic crack of the bullet going downrange. That's where the popularity of the 300 blackout comes from. They run a 200grn bullet subsonic (under 1050fls generally) and their guns are hearing safe. No supersonic rifle I have ever heard was hearing safe (or at least wasn't' hearing comfortable) to the shooter. But it wan't deafeningly loud like a regular rifle would be.