The M249 locking system is associated with which mechanism?

The M249 locking system is associated with which mechanism?

• A. Tilting bolt
• B. Rising block
• C. Gas operation
• D. Rotating bolt

Answer: (D)

The M249 uses a rotating bolt locking mechanism. In this design, the bolt contains locking lugs that engage matching recesses in the receiver or barrel extension to form a secure seal during firing. When gases drive the action, the bolt briefly retracts and then rotates to unlock, allowing the spent case to be extracted and a new round to be chambered, after which the bolt rotates again to lock for the next shot. The key point is that the locking action happens through the bolt rotating into place, not by tilting a bolt or by a rising-block arrangement. The term gas operation describes how the firearm is powered to cycle the action, but the specific locking method here is rotating bolt.

The M249 uses a rotating bolt locking mechanism. In this design, the bolt contains locking lugs that engage matching recesses in the receiver or barrel extension to form a secure seal during firing. When gases drive the action, the bolt briefly retracts and then rotates to unlock, allowing the spent case to be extracted and a new round to be chambered, after which the bolt rotates again to lock for the next shot. The key point is that the locking action happens through the bolt rotating into place, not by tilting a bolt or by a rising-block arrangement. The term gas operation describes how the firearm is powered to cycle the action, but the specific locking method here is rotating bolt.