The PhenX toolkit curates standard data collection measures for various topic areas, this specific one being for measuring social determinants of health. Using standard measures allows you to compare "apples to apples" with other research projects, as opposed to each...
Social Determinants of Health
Firearm Injury Prevention Dashboard
The Philadelphia Department of Public Health offers a data dashboard where you can find citywide statistics relating to gun violence and its upstream factors, like poverty and other social determinants of health. Firearm suicide data are also available.