I've been posting all over the place on all sorts of forums trying to
get some help with this one:

I'm using MAME32 (v. 85) with a Act Labs USB TV lightgun.
It works in Windows as a "mouse".
In MAME it calibrates and fires, but it doesn't "hit" anything.

I played Police Trainer and Aliens3:The Gun with trackball and the
lightgun to compare what happened. With the trackball, I have two
sets of crosshairs moving around. With the lightgun, one set of
crosshairs stays off the edge of the screen, which is where the shots
are going, despite it being calibrated fine for desktop use.

Any suggestions for things I could try?