Don't disappear, hmmmm...
Far be it from me to argue with 40 yrs. experience. However, at every trap/skeet range I've ever visited, there are thousands of bashed clay birds to be seen, lying downrange.
If they do disappear, it can't be all that quickly.
How/where do they go? Are clay birds water-soluble, or what? I admit I've never examined them more than superficially as I put them onto the target thrower. They seem to be some sort of formed, heated substance, sort of glassy-looking on the bottom. And it says on the box that they contain pitch, which I'm certain isn't water-soluble--it used to be used to seal the seams of wooden boats and ships, during the 1700's and 1800's.
I'm not arguing, just curious.