This tutorial shows how you can make a projectile that will hit the target and only that target; no matter what. Much like what you’d see in a game like World of Warcraft. This tutorial assumes you already have some sort of system for targeting.
You can check out my video tutorial series on RPG style targeting here:
If you don’t want/like/need a system like that, then you can always just use a simple line trace and store the actor hit.