Play with 2 players at night with enabled NVG´s and stand face to face from a distance of 100 m. Shoot at each other (but dont hit, for obvius reasons ^^) and look how the tracers look. Some are very long, some moving is very slow or some just behave like, i cant even explain ^^.

For the ricochets behaviour i recommened a DeerStand and shoot their roof from a distance of 100 meter... youll see that some tracers from the shooter are not the same as the viewer sees. AND: if you place another person in the Deerstand that looks for the tracers will see sometimes BIG LONG LINES that very slow falling down like a feather and not a Tracer.

If Video Footage is neede Please Let me know.