Grizbe is right. Laser beams *diffract* (spread out, to you).

A handy little equation for calculation the diffraction of a laser beam at a given range is:

RT = 0.61*D*L/RL

where:

RT = the radius of the beam at the specified range in meters

D = The range from the focusing lens or mirror in meters.

L = The wavelength of the laser light in meters

RL = The radius of the focusing lens or mirror in meters.

Depending on the raw power available, the wavelength of your laser and the size of your lens there is a very finite upper limit to the effective range of a laser weapon.

However - instinct tells me that the range listed in the book for a given weapon is simply 'effective range' - which is another animal entirely and takes into account things like accuracy and projectile speed.

Lasers have constant speed (subject to medium, of course), bullets start very fast and slow constantly over time. Bolts start slower, then accelerate, then slow again.