DAO firearms resolve some DA/SA shortcomings by making every shot a double-action shot. Because there is no difference in pull weights, training and practice are simplified. Additionally, the heavier trigger pull can help to prevent a negligent discharge under stress. This is a particular advantage for a police pistol. These weapons also generally lack any type of external safety. DAO is common among police agencies and for small, personal protection firearms. The primary drawback is that additional trigger pull weight and travel required for each shot reduce accuracy.