The mass shooting is always a sensitive topic in America and it hurts the society a lot. Some pieces of literature have already proved that mass shootings will have impacts on the stock market and investors’ economic behavior. We are going to narrow down the study area to the firearms industry instead of the total market. To explore the relationship between the stock return of firearms’ industry and mass shootings, we conducted a thorough analysis including descriptive and fundamental analysis, non-parametric test and a GARCH (1, 1) model. We first identify two uptrends after the event day, which is resulted from investor confidence and fear-based buying individually. Then, we use a GARCH model to quantify effects from shooting events on the firearms industry and found 0.181% and 0.533% incremental for daily and weekly in the event window. We also decompose the event window into two different windows according to two uptrends and have 1.1% and 0.521% abnormal return for each. The results show that the first event window is related to the date of mass shootings more closely while the second is not.