Optimism bias is common across health risk assessments, including firearm injury risk, and can have behavioral consequences. Using data from the 2018 California Safety and Wellbeing Survey, we examine whether optimism bias influences firearm injury prevention practices and policy support by comparing the characteristics, behaviors, and opinions of gun owners who believed having a gun at home is comparatively safer for themselves than for similar others ("Optimism Bias" group) with (1) those who unequivocally believe guns increase safety for themselves and others ("Always Safer" group), and (2) those who said they "don't know" or "it depends" in both the self and other scenarios (Uncertain group). Weighted multinomial logistic regression results indicated that gun owners in the "Optimism Bias" group were more often female, members of minoritized racial or ethnic groups, and new gun owners than the "Always Safer" and Uncertain groups; they also demonstrated greater support for 4 of 5 firearm injury prevention policies/interventions. Despite similar prevalence of owning a gun for protection, gun owners in the "Optimism Bias" group less often carried a loaded firearm or stored a gun in an unsecure way compared with the "Always Safer" group. Findings suggest that gun owners characterized by optimism bias, who acknowledged some risk associated with firearms, even if only or more so for others than for themselves, may represent a "movable middle" that is more receptive to firearm injury prevention efforts. Public health messages emphasizing other-oriented (vs. personal) risk and collective responsibility may be perceived as less threatening to the symbolic significance of guns to individual identity, thus enhancing effectiveness.