I was going to write an article about how to use perpendicular planes and simple distance algebra to implement perfect cylindrical hitboxes... but I was pre-empted by the quakelive team implementing it... damn

Instead, here is a perfect way to test how accurate the netcode/hitboxes are for railguns:
bind mouse1 "+attack;screenshotjpeg"

This actually causes another screenshot to be taken when you release m1, through which you can tell if the shot was a hit or not (crosshairpulse and the like)

Next week: How the "backwards reconciliation" netcode strategy ruins nuance by keeping client worlds out of sync.