What feature distinguishes the Mossberg model 590 shotgun from the model 500?

The feature that distinguishes the Mossberg model 590 shotgun from the model 500 is the detachable heat shield. The model 590 typically includes a heat shield that can be removed, which provides additional protection for the user from the heat generated during prolonged firing. This feature is particularly valuable in combat or tactical scenarios where rapid firing may occur, making it easier for the user to handle the shotgun safely.

In contrast, the model 500 does not generally feature a detachable heat shield, which is one of the primary distinctions between these two models. The other attributes of the shotguns, such as the adjustable stock, metal trigger guard, and built-in scope mount, do not specifically set the 590 apart from the 500 as clearly as the heat shield does. Therefore, the detachable heat shield is a defining characteristic that reflects the 590's design for military and law enforcement use, emphasizing its enhanced functionality in demanding situations.