No problem. Yes, you will eventually reach a threshold at which things cannot be rendered quickly enough to display properly. The same applies to the use of mesh for sword fights. You reach a speed at which you pan the texture on the mesh too quickly for Unreal to keep up with, and it begins to visibly create artifacts.
I can't remember the top of my head, but there is a setup for the blasting method that pans and tilts the same amount regardless of the length of the beam. This prevents your bullet from expanding and accelerating when you shoot something far or very close, so the tracer makes no noticeable difference no matter what you shoot