How about we put bad guys in jail, instead of punishing the millions of gun owners who haven't done anything wrong? A dramatic, double digit drop in murder rates for "Project Exile", vs. "challenges in discerning the effects of the ban"?
Richmond, Virginia, had a program in the 1990s. "Project Exile". Short version: Mandatory additional 5 years in jail if you use a gun in a crime, or if you're a felon found possessing a gun or ammunition. Crime went down 40%.
https://house.resource.org/106/org.c-span.153371-1.pdf
From page 2 of this report, "Since the project began, the results have been evident. More than
200 armed criminals were removed from Richmond streets during
the first year of Project Exile alone. An entire gang responsible for
multiple murders has been dismantled.
In 1998, murders were 33 percent below 1997, the lowest number
since 1987. In 1999, murders are down yet another 29 percent."
Compare this with the Assault Weapons Ban, which accomplished nothing. Here's the National Institute of Justice's report, describing how it had no effect in reducing crime:
http://www.sas.upenn.edu/jerrylee/research/aw_brief1999.pdf
"A number of factors—including the fact
that the banned weapons and magazines
were rarely used to commit murders in
this country, the limited availability of
data on the weapons, other components of
the Crime Control Act of 1994, and State
and local initiatives implemented at the
same time—posed challenges in discerning
the effects of the ban."