Which feature is NOT characteristic of the M4 rifle?

The feature characterized as not typical of the M4 rifle is its single-shot capability. The M4 is a select-fire weapon, meaning it can operate in multiple firing modes, including semi-automatic and fully-automatic (or burst, depending on the variant). This capability allows the rifle to fire multiple rounds with a single pull of the trigger, which distinguishes it from a single-shot weapon that requires the shooter to manually reload for each shot.

In contrast, the M4's gas-operated mechanism allows for efficient cycling of the action by utilizing the gas from ignited gunpowder to eject cartridges and chamber new rounds, enhancing its rate of fire and reliability. Being air-cooled means the M4 relies on ambient air to cool itself during operation, which is standard for most modern rifles. Additionally, the M4 is classified as a shoulder-fired weapon, designed for operation shouldered against the user's body, which promotes stability and accuracy while firing.

Thus, the M4's functionalities as a select-fire, gas-operated, air-cooled, and shoulder-fired weapon clearly establish it as a versatile firearm, making the characteristic of single-shot capability inconsistent with its design and operational features.