Accurate gun boresighting system

A device usable with a weapon having a barrel, comprising:

• an optical laser radiation source that emits laser radiation having a radially symmetric intensity profile declining in intensity from a center thereof;
• a mounting structure operably coupled to the laser radiation source having structure that engages the barrel and secures the laser radiation source substantially coaxially with the barrel;
• an optical receiver locatable remote from the weapon, the optical receiver including photodetectors located equidistant from and surrounding a central target site, the photodetectors being sensitive to the laser radiation emitted by the laser radiation source and each photodetector generating an electrical signal proportional to an intensity of the laser radiation received from the laser radiation source;
• a signal processor that processes the electrical signals from the photodetectors to generate an intensity gradient indicating comparative intensity of the laser radiation that is detected by the photodetectors wherein the intensity gradient presents a null point when the intensity detected by at least two compared photodetectors is equal;
• and
• a communicative link between the optical laser radiation source and the optical receiver.