Ge0rge: As an aside, we used to have firearms registered to their owner here in NZ - unsure when and why that changed, but it's odd that the police would choose to give that up?

It happened with the Arms Act of 1983.

As for implementation which was later, that was after when I left NZ for about a decade, I'd sold a rifle in about '84, filled in the details on my license and the buyer did the same on police forms, serial numbers etc and left the country.  That information (rifle serial number /ownership change) can't have been processed properly on any reasonably accurate system, as after I left, a series of letters were sent by NZ police to people living in residence I'd left in the '70s - and not even the address I was living at when I first got a gun license - perhaps where I was living when I first got a drivers license at 15.  About 1988 I dropped back in to godzone, I opened them (all the same - about updating my license for the firearm they should have known I didn't have, and warning of penalties if I didn't), I tossed them in the rubbish bin, jumped on a plane and forgot about it.  That's it - never heard a squeak from Police since, but if they dug back on records that they probably still have in some archive, and if they did some data matching, they'd probably think I was an unlicensed owner of a high power rifle, and have cause to pay me a visit, 34 years after I got rid of my last gun.

LOL - here you go from Wikipedia:

 

Increasing gun crime in the 1960s led to greater police use of registration records, which were generally inaccurate or out-of-date. A project to check the register began in 1967, and found that 66 percent of entries were inaccurate in some way, with many guns not to be found at all. Police thought that the register was largely useless, and that substantial resources would be needed to keep it up-to-date. It was believed that the government would be unlikely to provide the resources required to update the register and that it would be politically difficult to demand registration information from firearm owners. Various new laws were introduced in the 1970s and 80s, proposing more government checks, registration of shotguns (which had been abandoned) and individual licensing.

 

An internal police report in 1982 criticised the proposals, saying there was no evidence that registration of guns helped to solve crimes, and that registration would use time and money better spent on other police work. This policy was adopted by the government in the 1983 Act 

 

So actually Police wanted to give it up, as they weren't competent / well enough resourced to maintain an accurate register as early as the '60s.  Keystone cops LOL, though to be fair in those days they'd have needed a central team in Wgtn to maintain records and a daily update by NZ post from every police station in NZ.