I have a Benelli M4 shotgun. Because of import regulations, it comes with a 4 round magazine. I recently posted this video on how to swap out the 4 round magazine for a 7 round magazine.

The procedure is quite involved. It just occurred to me that this is a military shotgun. I find it incredulous that it would be this difficult to service a military weapon. Does the official military version assemble the same way or is it easier to swap out the magazine tube? Did Benelli "modify" it for the civilian version?