I needed to take one of my cats to the vet.

Report it to the RSPCA and the Police. Not sure how much action the Police would take, but I think the RSPCA would take note, and perhaps push the Police to do something.

You could also copy any letters to each of your neighbours telling them of the report, or ask the RSPCA if they suggest doing this, and put at the top of the letter that they have advised you to do this.

Local papers might get others in your village on your side, but I suspect that whoever has done this has broken the law, or perhaps their chuildren who they are responsible for have done so, and making them aware of may get them too worried to do such a thing again. If it is their chiildren, parent usually do not want them to start their life with a criminal record, or be alerted to the Police as nuisance makers. Some just don't care admittedly, but still worth a try.

Years ago now, a neighbour's son shot one of our cats with an air rifle, she was OK after having pellet removed. We guessed who it was immediately and reported it to the police and they took it very seriously indeed, I mean quite big time stuff rather than just a word in his ear...I presume more about the unloading of any gun of any description in public area rather than simply targetting  our cat...but made the local press and everything, who sent people round to their door to doorstep the family. So big it up, it might help.

I once knew a cat which was alleged never to have purred until the day it was shot in the head with an air rifle.