Wanted to learn how to print threads so I thought I'd design a moderator to fit 1/2 20 UNF threads. The version I'm presenting is version 8 as it took me 8 prints to get the female/male threads to mesh correctly. The unit that I printed is tapered to match the barrel diameter of my Gamo Urban. I provided other sizes based off the other rifles I have: Urban, Maverick and Avengers 22 and 25. I kept the threaded section outside of the air chamber to allow for more air expansion and added small vent holes to release pressure. Tested on my Avenger .22: without moderator it's 76db, with this moderator 55db Tested on my FX Maverick .30: without moderator it's 85db, with this moderator 66db Average 20db reduction!

Port size is 9mm so it should work for most calibers.