Quote Originally Posted by fullmetaljacket View Post
Could you be thinking of the stone bow?

My example is anything but silent and at over 35 ft lbs of muzzle energy in its standard configuration even a clay ball is going to make a mess of a small bird/mammal, you won't have much of specimen left.

The two halves could be unscrewed slightly and a spacer used between them to reduce the valve opening and lower the power of the original. I was told of a farmer who used such a set up to despatch geese when he had to in his yard. His wife was a sculptor and he used clay bay balls which were very effective for head shots without putting holes in his barn doors.