This is or was the big study on impact. Basically, the AWB had no useful impact on crime rates.
I heard it presented at a criminology meeting.
The reason for the failure was seen as:
1. Not enough time for an effect
2. Existing stocks of such weapons and accessories meet the demand of many
3. Substitution of weapons of equal efficacy (What no flash thingee on the end?) made cosmetic ban stupid.
We conclude bans are foolish. Antis conclude that much more draconian measures are needed.