...practical comabt advice for a gunslinger.
Shoot them until they stop shooting back.
ETA:
How do you get 4 hits (I'm presuming here you mean attacks) in one combat turn? You can only attack once per phase, so you'd either need to split your dice pool to use the Multiple Attacks free action, or have an initiative of 41 or more.
Example for my own character:
Base initiative of 10 + 3d6 gives a range of 13 to 28, or a maximum of three action phases. Each phase could consist of one Simple Action (Take Aim) and one Simple Action (Fire Semi-Auto, Burst Fire, or Full-Auto), for a total of three attacks at full dice pool values.
Alternatively, each phase could consist of one Simple Action (Take Aim) and one Simple Action (Fire Semi-Auto, Burst Fire, or Full-Auto) combined with a Free Action (Multiple Attacks). Recoil could become a problem, and I'm not 100% sure you can use Take Aim and Multiple Attacks as Take Aim specifically states that you cannot take any action, including free actions, between taking aim and firing your weapon. But, multiple attacks states that it's combined with an attack action, so may or may not be allowed. In any case, that leaves up to 6 opponents attacked in a single combat turn, but at half dice pool.