The Army's favorite buzzword "modular" went to town on this new M-26 MASS Shotgun. You can stick it under your M-4 Rifle or you can make it a stand alone shotgun that you whip out of your backpack. The US Military loves their lethal accessories.
Sure the M-26 isn't exactly brand new. It's been around since 2012. But It's relatively new compared to the Mossberg 500 shotgun which has been around since the 1960's. The Mossberg 500 has been used by military and police forces to great effect since then. It's a legendary piece of equipment.
The real question is should you mount this shotgun to the bottom of your M-4 rifle or not?