Do velocities stack?

If I launch a projectile with 6k initial velocity from an actor moving at 1k, does a projectile launch with 7k like IRL or 6k anyway?

The thing is I am making a targeting assist system for shooting moving objects and it becomes more and more inaccurate with distance and I’m not sure why.

The projecitle velocity is relative to the world rather than origin.
You can set the initial velocity to be (6k+source_actor_velocty)