The 6.8 NGSW
As well-loved as the 5.56mm is, it has, in recent years, shown some limitations. Because it is a light bullet, the 5.56mm does not do well against hard cover, or at extended ranges. It might not be the best rifle to take into long-range firefights in mountains where there are a lot of rocks for cover. This, incidentally, is a good description of the fighting that has taken place in Afghanistan for the last two decades. In response to this, several services went to new weapons, like the SCAR, or old ones, such as the M14, in a larger caliber, to get the job done. But that was a stopgap solution, and now the Army is in the process of developing a new bullet, the 6.8 New Generation Squad Weapon, or NGSW.