What is the barrel length of the M16A3 service rifle?

The correct answer is that the barrel length of the M16A3 service rifle is 20 inches (508 mm). The 20-inch barrel is designed to allow for optimal velocity and accuracy, which is essential in military engagements. A longer barrel can enhance the stabilization of the bullet and result in improved accuracy over longer distances, which is a significant advantage for a service rifle.

The other stated barrel lengths do not match the specifications of the M16A3. For example, the 16-inch barrel is typical for carbine variants, such as the M4A1, which are designed for compact and maneuverable operation. The 21-inch and 24-inch barrels exceed what is standard for the M16A3 and would typically be found in specialized rifles designed for long-range precision shooting. Understanding the correct dimensions of military rifles, including the barrel length, is crucial for effective weapon handling and deployment in various combat situations.