Australia - here's some quotes from an interesting article. It also discusses the illegal gun present in many countries:
And even that underwhelming estimate gives the authorities the benefit of the doubt. Three years after Australia’s controversial ban was implemented, when 643,000 weapons had been surrendered, Inspector John McCoomb, the head of the state of Queensland’s Weapons Licensing Branch, told The Sunday Mail, "About 800,000 (semi-automatic and automatic) SKK and SKS weapons came in from China back in the 1980s as part of a trade deal between the Australian and Chinese governments. And it was estimated that there were 1.2 million semi-automatic Ruger 10/22s in the country. That's about 2 million firearms of just two types in the country."
The Australian Shooters Journal did its own math in a 1997 article on the “gun buyback.” Researchers for the publication pointed out that the Australian government’s own low-ball, pre-ban estimate of the number of prohibited weapons in the country yielded a compliance rate of 19 percent.
As Tom Servo said - Cuomo has served the RKBA well in the debate. When you say that they will take your guns - people think you are nuts. Thanks Cuomo for the quote.