Responses
Putting into consideration that the setting in this story (probably) is in the USA, it isn't much of a shock that he's able to acquire a firearm. From your local store even. Gun laws are practically non-existent in some states there. For now, at least. Some cases, they just need an ID and done. Gun in your possession.
Where he even get the gun? Why does he have one? If someone could properly develop this story I would be grateful!