Friend sent me this yesterday - haven't read it yet.
Langmann, Caillin. 2012. Canadian Firearms Legislation and Effects on Homicide 1974 to 2008, Journal of Interpersonal Violence, Vol. 27, No. 12. p. 2303.
From the abstract: "This study failed to demonstrate a beneficial association between legislation and firearm homicide rates between 1974 and 2008."