Recently one of the members of our local gun club brought me a Cometa 300 in 4.5mm (.177). He'd dug it out of storage and proceeded to try and shoot it, and couldn't hit anything. So he then tried a shot at the water in the swimming pool to see how far off his sights were. And nothing. Not a ripple. So THEN he looked down the bore and found it blocked so he pushed a thin rod through it and all the pellets were right there inside. Today I got the chance to open it up.

Yep, the piston seal was completely disintegrated. The miracle is that it still managed to push several pellets far enough into the bore that he could keep on inserting another one for each shot.

The rest of the rifle is in fairly decent shape, but clearing out the compression chamber is going to be "fun". A new seal by Jim Maccari and a bit of proper lube should go a long way towards putting this rifle back in operation.