The .223-caliber [5.56-mm] cartridges recoil is negligible compared with the .30-caliber cartridges fired in the Springfields, M-1 Garand rifles and M-14s that were used by American troops from 1903 until 1966. Soldiers have persistently criticized the round for its lack of stopping power. The small-diameter bullet travels at high speed, and frequently passes through enemy soldiers without inflicting immediately visible injury.

The 5.56-mm NATO cartridge may be identified by its appearance, the painting of projectile tips, the stamping of the manufacturer's initials and year of manufacture on the base of the cartridge case, and the markings on the packing containers. When removed from the original packing container, the cartridge may be identified by its physical characteristics. The M193 and M196 cartridge for the M16 can be fired with the M249, but accuracy is degraded; therefore, it should only be used in emergency situations when M855 or M856 ammunition is not available.