I tried a bunch of different things on my Avenger including a DonnyFL Tanto on a DonnyFL adapter. That worked fine, I measured the sound at about 85db at one meter to the side and about a foot in front of the muzzle. My Avenger is a 25 tuned to shoot FX 25.4s about 930 fps. The only thing I did not like about this was the added length. I think the Avenger is already too long without the moderator or adapter added. Then I got some printed moderators from a nice guy who asked me to test them. I was surprised when an in shroud moderator tested at about the same sound level without any added length. Part of the reason it worked as well as it did is I drilled some holes in the back of the shroud when I was testing other shroud modifications.
Pellets hitting a piece of paper results in a sound of about 85 db. I thus consider a gun at about the same sound level to be quiet enough.
My P35s are at about the same noise level with a hair curler and a half and 3 baffles in their shroud. I read that the Taipan has an effective shroud and is therefore pretty quiet. Other "high end" PCPs seem to need moderators. If there is enough volume in the shroud, modifying that seems like a cheaper and equally effective solution that involves less, if any, added length. One guy reported success with a compact Prophet but said the standard one doesn't have enough volume in the shroud.
