Why was the M14 difficult to control in automatic fire?

The M14 rifle was difficult to control in automatic fire primarily due to the extreme recoil generated by its 7.62-mm NATO cartridge.1

While the M14 performed well as a self-loading rifle, the high power of the ammunition made it "totally unmanageable" when used in its fully automatic configuration. This lack of control, combined with the weapon's significant weight, ultimately led the U.S. military to seek more effective alternatives, such as the M16 rifle, which utilized a smaller, high-velocity 5.56-mm cartridge to produce a more manageable recoil.12