A trigger is a mechanism that actuates the function of a ranged weapon such as a firearm, airgun, crossbow, or speargun. The word may also be used to describe a switch that initiates the operation of other non-shooting devices such as a trap, a power tool or a quick release.

What is difference between single action and double-action?

An easy way to remember the difference between Single and Double Action is to remember that a Single Action trigger performs just a single action, dropping the hammer, which fires the round and a Double Action trigger performs two actions in one trigger pull: cocking the hammer and then releasing it.

What is the point of double-action?

A double-action trigger, also known as double-action only (DAO) to prevent confusion with the more common hybrid DA/SA designs, is a trigger that must perform the double function of both cocking and releasing the hammer/striker.