Night of the Living Dead (1968)
 

I wanted to this out there and see if anyone was interested. I don't believe the gun listed on the IMFDB page is correct. I did a documentary on the zombie genre and the actor who played the police chief, and provided many of the firearms, told me in great detail what the gun was. It seems to be very much a specialized firearm, though I can't remember what he had said (I got it on camera, but it's with the editor at the moment). I do, however, have a photo.

Thought it might interest some.

http://a1.sphotos.ak.fbcdn.net/photo...90_6119909.jpg