What manner of franken gun is this? ;)

[MT2008]

Hmmm, I'm surprised that the gun isn't on the page. As much as I appreciate all of the work that Ben does for the site, I do wish that he would take more time to do pages right and get all of the guns and the best screencaps (as I do).

With that being said, I'm in the camp that this is indeed just a Benelli M1 Super 90 that has been given a fake extended magazine. You may recall (since you worked on the page) that Alien Nation, which is the first documented movie appearance of the Benelli M1 on IMFDB, also featured a gun which had fake extended magazines attached to it. (I added some detail to the page last year which explains why I believe that the drum magazine used on that gun was likely a non-functioning prop.) The pistol grip, admittedly, doesn't look like the factory Benelli grip, but it might have been taken from a different gun and then modified to fit to the Benelli's receiver, or else a custom job that the armorer provided at the production's request.