I'll be interested to see silencer shop's independent tests, but Griffin's own video shows 300 BLK at 125.5 db in full size configuration. 138 on .308. Not too bad. Here's the video:
https://m.youtube.com/watch?v=ZCP4AF8Hv-k
https://m.youtube.com/watch?v=ZCP4AF8Hv-k