Which type of ammunition is used during mechanical training for the M249 AR?

The type of ammunition used during mechanical training for the M249 AR is the M199 Dummy round. Dummy rounds are specially designed for training purposes; they simulate the weight and feel of live rounds without containing any propellant or projectile. This allows personnel to practice loading, handling, and other operational procedures safely, without the risk associated with live ammunition.

Using dummy rounds, like the M199, enables soldiers to become familiar with the weapon's mechanics and functionality in realistic scenarios, which is critical for ensuring proper performance during actual operations. The absence of explosive components in dummy rounds means that trainees can focus on the manipulations and procedures relevant to the weapon while reinforcing muscle memory and handling skills.