heavy bolts, the inertia of dropping the gun can cause the bolt to come partially open, rendering the gun unfireable until the bolt is manually closed all the way. To prevent this, the Carbine uses a bolt lock that locks the bolt securely closed so that a fall will not dislodge it. A slight pressure on the trigger or on the bolt handle, however, will disengage the bolt lock so that the bolt can move for firing or clearing the action. In addition to caliber, the Carbine also comes with a choice in iron sights. The standard model uses notch-and-post sights, while the GR models are equipped with ghost ring rear sights. The ghost ring sights cost more, but they are generally considered better for defensive purposes, as they allow faster sight alignment under poor lighting conditions plus a longer sight radius for greater accuracy. The Carbine also has Ruger-style scope bases built into the receiver, allowing optical sights to be easily and securely mounted. References External links User Manual Police weapons Semi-automatic rifles of the United States Police Carbine Carbines