Generally speaking, there are three types of guns: rifles, shotguns, and handguns. Of course, it's far more complex than that and there are myriad sub-categories within those groups. Then there are the many different action types you find in various types of firearms.
Suspense can be created with these literary devices: Dramatic irony (the reader knows something the character doesn't)Pace (fast or slow action)Foreshadowing (hints about what is to come)
a state or condition of mental uncertainty or excitement, as in awaiting a decision or outcome, usually accompanied by a degree of apprehension or anxiety. a state of mental indecision.