https://www.youtube.com/watch?v=RH68hiftyho&t=1234s (at about 15:53 he talks about the moderator)
https://www.youtube.com/watch?v=PmXkSaCs4GQ (at about 2:26 he briefly talks about the moderator)
There are other videos that review the rifle that also discuss the moderator. Just search on "Air Arms S510 Tactical" on YouTube.