Since Glocks are single action, I should think accidental discharges are quite rare.
Glocks are striker fired. Racking the slide loads a round and cocks the striker. Since it doesn’t have a decocker, the only way to uncock it is to remove the magazine, rack the slide to remove the loaded round in the chamber and then pull the trigger. You can’t remove the slide without pulling the trigger first, so some ND’s have happened when the operator forgot about the loaded round in the chamber.
“Since Glocks are single action, I should think accidental discharges are quite rare.”
There’s been a lot of talk about negligent discharges with Glocks, but no, they do not ever fire unless you press the trigger. They are one of the guns designed to meet extremely stringent military drop tests. If your Glock fires, is is because you pulled the trigger.
Double action. The firing pin is only partially back when a round is chambered. The pin moves rearward as the trigger is pulled — and then releases. Glocks are DAO triggers.