Small arms the U.S. will be equipped with cartridges of caliber of 6.8 mm, according to Popular Mechanics. At this point in American M16 rifles used ammunition caliber 5.56.
The 5.56 is obsolete, according to U.S. army. Larger shells will get M4A1 and the M249 machine gun, standing in service in the U.S. army. This change calibers associated with the use of Russia and China in a more durable body armor, which the old calibre can’t cope.
The 5.56 is also used in the us army since the Vietnam war. Now in the United States to move to more advanced technologies. «A new cartridge with a larger diameter can hold more gunpowder in the casing, creating higher chamber pressure in pounds per square inch to pull the bullet down» — emphasizes the publication. The army are armed with new ammunition in 2023.