Over the last 20 years, the firearm crime rate has dropped, according to the Bureau of Justice Statistics, from 6 victims per 1,000 residents in 1994 to 1.4 victims per 1,000 residents in 2009. The 1.4/1000 is the same rate as in 2004, the last year in which the “assault weapons” ban was in place. Part of this is from an overall decline in violent crime over the same period, but that doesn’t account for all of the improvement. Firearm crimes accounted for 11% of all violent crime in 1993 and 1994, but was 8% of all such crime in 2009.
This decline took place in an era where gun sales increased and carry permit laws were liberalized. It may assume too much to claim that that increased gun ownership and carrying caused the decline, but it’s clear that the correlation runs in that direction and not the opposite.