I unhooked my damage from lasers from the server frame rate by giving them a timed damage tick delay.
Whenever they damaged someone, they would save a ent-id and gameclock pair for that player in a list. The gameclock value would be the current frame clocktime + the damage tick delay. every server side think, the first thing each beam did was go through it's list of damagees and remove them if their clockvalue had been past by the current gametime. When the beam finds entities it can damage, it quickly compares them to the ids in the list. New ones are given damage and an entid,clock pair while existing entities in the list are passed over.
This removes the finger of god damage that you are dealing with at the moment.