Unless Irish rabbits are a lot different then American rabbits, the noise of a firearm is not a factor in hunting them.
If you walk them up or hunt with dogs, they are already scared and running when you get a shot.
Otherwise, they are setting very still in a clump of grass or brush pile, trying to hide from you, when you shoot them in the eye.
In either case, a silencer is not necessary.
Sorry I can't make a suggestion.
rc