A friend of mine years ago made a suppresser for a .22. With high speed HP's all that could be heard, was the click of the striker, just like a dry fire then the bullet striking the target board. NICE!
I'd like one like that on the .17AH - but just to cut the ear-drum sting a bit. It runs 3,925fps with 20gr. Vmax's. Getting it down around 120DB - legally, would be fine - but is not to be.