Citation(s) from the GunPolicy.org literature library
Reuter, Peter and Jenny Mouzos. 2002 ‘Australia: A Massive Buyback of Low-Risk Guns.’ In: Evaluating Gun Policy: Effects on Crime and Violence. Editors: Philip Cook and Jens Ludwig, p. 130. Washington, DC: Brookings Institution Press. 1 December
The most targeted population survey of gun ownership was conducted by Newspoll; the resulting estimate was approximately 2.5 million firearms in 1997, after the gun buyback.
If that is approximately correct, it suggests that there were about 3.2 million firearms in 1996 and that the buyback led to the removal of approximately 20 percent of the total stock. In U.S. terms that would be equivalent to the removal of 40 million firearms.