The Mossberg 835 Ulti-Mag is the first pump shotgun with a 3.5" chamber "magnum-capable barrel. All other shotguns are designed to fire 2 3/4" and 3" shells. Overboring the barrel to handle the additional power was the first thing Mossberg did to support a 3.5-inch magnum shell. The Mossberg 835 shares the same dual extractors and two action bars as the 500 and 590 versions but adds more punch while maintaining the smoothness of the shotgun. The back-bored barrel offers exceptional comfort from felt recoil despite having more power because it has less internal friction. The back-bore barrel, though, is the Mossberg 835's most distinctive characteristic. The Mossberg X-Factor Waterfowl Choke is made to provide the user with more consistent patterns and less muzzle flip for an improved shooting experience. The greatest feature of this choke is that it can be installed without the use of additional tools and that, if necessary, it is simple to clean and replace