Because the light gun is inherently inaccurate, the time value calibration routines average two valid sensor readings into one value. Even so, expect x,y values to be plus or minus three pixels (or more) from the pixel the gun is actually pointing at.
Example programs showing how the light gun and the event broker interact are provided in the 3DO:examples:Eventbroker folder. This folder is automatically installed with this version of 3DO Portfolio.