Silencers on rifles, both 22RF and big bores, are very popular in NZ now. The best ammo I find for the 22RF is the standard sub-sonic LR ammunition preferably with a 40gr hollow point bullet. As all sub-sonic 22RF have much the same MV of about 1040fps the heavier bullet seems to make most semi autos operate reliably. I find the Winchester sub-sonic with the 40 gr bullet and big hollow point is very accurate and a good killer at normal ranges for small game with the 22RF and they work very well in my Gevarm semi auto. This same ammo is great in the Ruger 10/22 as well, one of our most popular 22ZRF rifles in use today.

Many hunters using cartridges suitable for our deer, tahr and chamois animals are now using silencers which obviously reduce noise but also usually some recoil, and most users report better accuracy, probably more due to less noise and recoil rather than any real effect from the silencer on bullet flight or what ever. Often the bigger bore barrels are shortened slightly to keep overall length reasonable and maybe a new crown job does improve accuracy of some rifles when a silencer is fitted.

Silencers used to be 'illegal' in NZ all though not actually by law just by Police intolerance of them because of a misguided notion they would be used by criminals and where they were sold and used, they were called suppressors. A more realistic approach and changing of the old guard in our Police and Government have seen an acceptance of the use of silencers and are very much promoted and encouraged now in some circles from a health and safety point of view for protecting the hearing of shooters and bystanders.

As far as I'm aware they are not 'required' anywhere in NZ for hunting although this may change for some shooting clubs or on some shooting ranges.