For the sake of an example, you have an assault rifle actor, and you want to add a component that merely marks a relative location on that model (for a grip point, a red dot sight location, the end of the barrel, etc). The component’s sole purpose is to mark that location, so that the blueprint can do the rest.
What component makes the most about of sense for that purpose?
So if it’s a skeletal mesh you can use a socket by adding one to the skeleton. However, in this example with an Actor, you want to use a “Scene Node” component! It’s an invisible point that you can use for reference!
