https://www.youtube.com/watch?v=ENIkHL10iZs
In the original video, I think that you can hear the “Snap-boom” of rounds whizzing by. The “Snap” is from a supersonic round going by, the “Boom” is the weapon sound.
Compare sounds - 125 yards downrange, 5.56 mm, unsuppressed and suppressed.
https://www.youtube.com/watch?v=cjfm4d0DcDg
🐷
That’s exactly the sound. I worked the pits at 600 yards a couple of times. Same thing but a longer separation of sound.