Andy Freeman said:

Why doesn’t Lambert tell us about pre-control crime and murder rates
and trends in Oz and compare them to post-control rates and trends?
If gun control actually worked in Oz, the introduction of controls was
associated with a good change in the rate trend. Could it be that
there wasn’t a good change associated with the introduction of
controls?

“Homicide: The Social Reality” by Alison Wallace, published in 1986 by
the NSW bureau of Crime Statistics and Research is an extensive study
of all homicides in NSW from 1968 to 1981. This contains a graph
detailing the homicide rate in NSW from 1900-1981. I shall attempt
reproduce it in ASCII: (Vertical scale is homicide rate per 100 000
population, horizontal scale goes from 1900-1977 (I left off the last
four years so it would fit in 80 columns))

3      *  ***
2.8
2.6          **   *   **
2.4            * *
2.2  *   *
2.0             *  *            *
1.8     *           *   *      *      *             **        * *  *
1.6                      *   ** ***        *   *  *   **  **   ** **        *
1.4**                *              ** *      *    **   *   ***  *   * * *
1.2                                *     **  *  **    ** *      *     *
1.0   *                   * *                    *
0.8                    *            *
   0         1         2         3         4         5         6         7
   012345678901234567890123456789012345678901234567890123456789012345678901234567

The population of NSW increased from 1.3M to 5.0M over this period,
which explains why the year to year variation has decreased. Now,
when was gun control introduced in NSW?

The 1920 Gun Licence Act required all persons wishing to purchase,
use, carry or possess any gun to take out a licence for each gun in
their possession with the definition of “gun” including both long arms
and pistols. NSW gun laws took on their present form in 1927 when the
restrictions on long arms were relaxed.[1]

The NSW homicide rate did not change significantly from 21-77,
averaging about 1.5. From 1900-20 it was much higher, averaging about
2.4. I’m afraid that no statistics exist for the gun homicide rate
before 1968. There would appear to have been a dramatic decrease in
the homicide rate following the introduction of gun controls.

[1] Proceedings of a Seminar on Gun Control, Institute of Criminology,
Sydney University Law School, 8 May 1985 p17.