Rifle is a more effective weapon from a far distance. Also, it will be better to activate all drugs in such cases when fighting I mean.
You can also use tec9 for close fights. After reducing the opponents HP with Tec9, you can switch to combat shotgun and kill them easily.
In addition, ak-47 can be preferred for close fights instead of the combat shotgun, and I recommend using the M4 for far distance.