this gun was a total pain in the ass for me but when u get it working it works perfect.
You have to use smogs guncon 2 drivers not the EMS ones, they really do work.
Once u get them to work in windows where it acts like a mouse you have to set it up as like mouse 2 or mouse 3, mame will choose, then configure it in mame control menu. prolly wont work cause your using EMS drivers