Australia is often held up as a global example for strong gun laws because of the sweeping reforms after the 1996 Port Arthur massacre. 

But since then, the number of firearms in Australia has increased by 25 per cent to more than four million, according to figures from The Australia Institute.

In light of this week's fatal shooting of two Victorian police officers, we examine what's behind the rise in gun ownership - and whether Australia's gun laws are still keeping people safe.