Abstract: Introduction: Year 2021 had the highest number firearm suicide deaths in U.S. history, with veterans representing 62.4% of firearm suicide deaths. The study objective is to understand motivations for firearm ownership, storage practices, history of mental health disorders and suicide risk in servicemembers, as reported by family members. Methods: Data were obtained from a case-control psychological autopsy study of 135 suicide decedents in the U.S. Army compared to a probability sample of 255 living controls, who are also service members weighted to be representative of the Army. Next-of-kin and Army supervisor informants participated in structured interviews and assessed reasons for firearm ownership, and storage practices. The military medical record provided lifetime mental health history of suicide decedents. A subsample of 123 personal firearm owners (n=31 cases and n=92 living controls) addressed the study objectives. Multivariable logistic regression analyses were constructed to examine predictors of unsecured firearm storage practices. Results: Family members reported safety/protection as the main reason for suicide decedents' firearm ownership, which was significantly associated with unsecured firearm storage practices (OR=3.8, 95% CI, 1.65, 8.75, x(2)=9.88, p=0.0017). Ownership for safety/protection and lifetime history of Generalized Anxiety Disorder (GAD) from the military medical record (OR=3.65, 95% CI, 1.48-9.02, x(2)=7.89 p=0.0050) predicted unsecured storage. Conclusions: Ownership for safety/protection and the presence of clinically significant anxiety predicted unsecured firearm storage practices. Future research examining motivations for gun ownership for safety/protection, anxiety, and unsecured storage practices may help target interventions to prevent suicide.