The US Army is planning on a new rifle cartridge. And new rifles to shoot the new cartridge.

 The modern rifle appeared after the US Civil War, say 1870 or so.  These were Winchester and Marlin lever actions, early bolt actions, and other competitors.  They were mostly chambered for a .30 caliber center fire cartridge with enough power to take American game, such as elk, deer, buffalo, bear, and wild hog.  This rifle cartridge served well from the Spanish American war up thru WWII. Korea and Viet Nam. 

   During WWII the troops fell in love with full automatic weapons, the Thompson submachine gun and the M3 “grease gun”.  From the soldier’s point of view, the ability to point the weapon and hose down an entire enemy unit with one quick “BRAP” could be life, should they encounter a strong enemy unit in combat.  The American WWII sub machine guns fired pistol ammunition, the .45 caliber round used in the Army .45 automatic pistol.  The pistol run lacked the power of rifle rounds, but the recoil was light enough to permit full automatic fire from a 7-9 pound shoulder weapon.  The regular rifle rounds kicked so hard that they just drove the rifle up until it pointed at the sky. 

   After WWII the Army adopted the full automatic M16 rifle.  To get the recoil down enough to make the gun usable in automatic fire, the power of the M16 round (5.56 mm) was reduced quite a bit.  The real riflemen in the army still liked the WWII 30 caliber round, it reached out further, it could penetrate more body armor and it made a sniper more effective than the 5.56mm round from the M16.

   So after decades of grousing about the lack of power in the standard 5.56 mm round, the Army has announced it wants a 6.8 mm round (.270 a civilian gun shop would call it) The army claims that the small increase in bullet diameter will give a round with ballistics nearly as good as the antique .30 caliber rounds and light enough recoil to allow fully automatic fire from a 7-9 pound rifle.  

   Needless to say, adoption of the new recoil will require the army to replace all the M16 rifles with whatever will fire the 6.8mm round. And all the machine guns too.  This could become very expensive.