What is that shotgun in the movie?

My guess is a Remington 870 but I have to re-watched the movie to check it out and be sure but the shell holder is nothing special it is something that can be added to almost any pump shotgun, Remington 870s have is a very popular gun and has been around for over 50 years so due to its popularity there are a lot of companies that manufacture accessories for the gun.

Here is a picture of my 870 next to my double barrel coach gun it looks similar to the one in the movie.


edit

Mossberg is also a popular pump that is similar to the 870 so it could be something other than the 870

http://img.photobucket.com/albums/v308/silvercorvette/DSC00990.jpg

Here is a picture of the ATI stock with shell holder

http://www.goodguysguns.com/ATI/shotgun_products/ATI_Top_Folding_Shotg un_Stock.html

Of all the things I have lost I miss my mind the most

Wrong it's a spas 12