"... the 1,700 handguns collected by the SGBBP represent less than 1 percent of handguns in Seattle homes. Even under the unlikely assumption that guns turned in during buy- back programs are as likely to be used in a crime as the guns not exchanged, the effect of removing 1 percent of guns from the community on rates of firearm crimes is negligible. In 1979, Cook found that a 10-percent reduction in the prevalence of firearm ownership was associated with a 4-percent reduction in the robbery murder rate (23).
The Seattle buy-back program failed to reduce significantly the frequency of firearm injuries, deaths, or crimes. The evaluation was incapable of detecting small changes in these rates, given the year-to-year and month-to-month variation. A much larger number of guns would need to be collected to impact on firearm morbidity and mortality."