The M26 Modular Accessory Shotgun System (MASS) is a developmental under-barrel shotgun attachment for the M-16/M4 family of United States military firearms. It can also be fitted with a pistol grip and collapsible buttstock to act as a stand-alone weapon.
The M26 MASS is a militarized version of the Lightweight Shotgun System, developed by C-More Systems and manufactured by Vertu Corporation and originally marketed toward special operations forces. It attracted the interest of soldiers being deployed to Afghanistan who wanted to reduce the number of individual weapons they had to carry by using a shotgun as a rifle attachment instead of a discrete, separate weapon.
— In-game description
The M26 MASS is an Assault class underbarrel attachment or stand-alone weapon that is unlocked after reaching 38000 Assault score. It is a straight-pull bolt-action shotgun which is located on the left side of the weapon. The gun itself features similar iron sights to the PDW-R, P90 and Mk11 Mod 0. It can use the following types of ammunition, unlocked in this order:
An important thing to note about the M26 MASS in comparison to other shotguns, is that it is noticeably more quiet and, in a hectic firefight, can be difficult for enemies to distinguish from background sounds, making it extremely useful for flanking maneuvers. While not having quite as fast a rate of fire as other shotguns, the MASS can still prove a handy addition when coming around corners or sneaking up on enemies. The M26 MASS is better suited for close quarters combat than the M320 BUCK. The M26 MASS fires 12 pellets/darts per Buckshot/Flechette shell, same as the 870 MCS.
It should also be noted that while aiming down sights with the Underslung Rail and the M26 MASS on compatible guns, the player will use their primary weapon's iron sights or other optics attached, in addition to being able to use third-tier attachments such as the laser sight.
— Battlelog Description
The M26 MASS is a gadget featured in Battlefield 4 as an Assault class under-barrel attachment or stand-alone gadget. It fires 12 Gauge Buckshot, with other ammunition types unlocked by progression with the Assault kit. Separate stats are kept for each ammunition type in Battlelog.
Unlike in Battlefield 3, the standalone M26 MASS is equipped with a Reflex (RDS) by default, with no iron sights available. An underslung M26 MASS can use the same accessories as its attached weapon, aside from barrel modifications.
For purposes of progression, the M26 MASS contributes to the player's Shotgun score. Since it is unlocked by the Assault class, shotguns other than the QBS-09 can be unlocked using the M26 MASS.
- Originally, the M26 MASS had Service Stars that could be earned, but without earning Proficiency and Mastery Dog Tags. This was later fixed by a patch.
- In patch 1.04, the M26 MASS was affected by a glitch in that substantially increased or decreased the damage of the weapon if a player equipped the MASS on their weapon's Underslung Rail while also using a Heavy Barrel. The glitch essentially made it so that when the MASS is fired, each pellet had the same damage of a single shot from the main weapon allowing for a potential maximum damage of 403 if used in conjunction with a G3A3, while at the same time making it so a slug round does the damage of a single assault rifle shot, making it very ineffective. This glitch grew worse when using the M26 DART. DICE had acknowledged this as an unintended feature and removed it via the 1.05 patch.
- The end-of-round unlock description of the M26 MASS incorrectly states that it is semiautomatic, even though it's a pseudo-bolt action shotgun. This is a developer oversight.
- The M26 MASS' magazine used to disappear when pumped if equipped standalone.
- The M26 MASS shares the same first-person firing sound as the M320.
- If the player is killed while having the M26 MASS equipped on a rifle, and then revived, when the player switches back to his rifle, his hand will be clipping through the M26 and placed where it normally is without the M26 MASS equipped. Re-equipping the M26 will fix this.
- Only when mounted on the CZ-805, the M26 FRAG has no killmessage name: the killfeed simply says "KILLED". The M26 MASS instead states the player got a kill with the FRAG version of the M26. When using the M26 DART attached to the CZ-805, kills will incorrectly be displayed as M26 FRAG kills, and thus, there is technically no killfeed message for FRAG or DART kills. Only BUCK and SLUG ammo types have proper killfeed messages. This bug appears to only affect the M26 attached to the CZ-805.
- In earlier stages of Battlefield 4, the M26 had camouflage applied.
- Unlike in Battlefield 3, Service Stars are now earned separately for each ammunition type.
- When an assault rifle is equipped with a Tactical Light (flashlight) and the player switches to the M26, the flashlight will turn itself off automatically, and if Canted Ironsights are equipped, the M26 will default to using those instead of the primary weapon's iron sights or optics. The same also happens to all laser sights.