The rotating bolt locking system is characteristic of which weapon family?

The rotating bolt locking system is characteristic of which weapon family?

• A. MG3
• B. M4A1 Carbine
• C. M4/M16
• D. M16A2 Rifle

Answer: (C)

Rotating bolt locking is a hallmark of the AR-15/M16/M4 family. In these rifles, the bolt head carries locking lugs that engage recesses in the barrel extension. A cam pin drives the bolt to rotate about its axis as the bolt carrier moves, so the lugs lock the bolt in place during firing and create a tight seal in the chamber. When the gas system moves the bolt carrier rearward, the bolt unlocks by rotating again, allowing extraction and ejection before the next round is fed. This rotating locking mechanism is a defining feature of this family and is shared by the M4 and M16 variants, including the M4A1 Carbine and the M16A2 Rifle. Other weapon systems use different locking methods, so they don’t share this characteristic.

Rotating bolt locking is a hallmark of the AR-15/M16/M4 family. In these rifles, the bolt head carries locking lugs that engage recesses in the barrel extension. A cam pin drives the bolt to rotate about its axis as the bolt carrier moves, so the lugs lock the bolt in place during firing and create a tight seal in the chamber. When the gas system moves the bolt carrier rearward, the bolt unlocks by rotating again, allowing extraction and ejection before the next round is fed. This rotating locking mechanism is a defining feature of this family and is shared by the M4 and M16 variants, including the M4A1 Carbine and the M16A2 Rifle. Other weapon systems use different locking methods, so they don’t share this characteristic.