It doesn't actually shoot anything, because its really just a battery-powered projector. The gun comes with a 16 page booklet of cellophane strips of printed images of ghosts, devils, spiders, etc., which are torn out on their perforated edges and slid into a slit on the gun's side.
The stock of the gun has a bit of play in it, kind of like a joystick, and can be moved a few inches in any direction, independent of the front end. Moving the stock also moves an internally mounted pin, which punctures the cellophane target when you pull the trigger, leaving a visible hole in the projected image, wherever the pin happened to be aimed.
I count exactly 1,088.
There was also a white "Moving Monster" version of the gun, with different target images.
Image from PlaidStallions. Be sure to check out their excellent book of dime-store toys, Rack Toys:Cheap, Crazed Playthings.
When I owned one of these back in the 70s, I always thought the gun kind of resembled Madame Medusa's from Disney's The Rescuers, and would use it as such for Rescue Aid Society role-play sessions (yes, that was a thing in my circle of friends!)
Here's scans of all the Ghost Gun targets.