The trigger mechanism is the heart of every pistol, directly impacting both shooting accuracy and safety. In this article, we break down the differences between the classic SA (light pull, requires cocking) and DAO (long, heavy pull for enhanced safety), the hybrid DA/SA mode, and modern Striker-Fired systems (without an external hammer) made famous primarily by Glock and its Safe Action system. Understanding these acronyms will help you choose a firearm that best fits your shooting skills and intended use.
TL;DR: The design of the trigger mechanism fundamentally dictates a pistol's behavior when firing and its level of safety. Among classic hammer-fired systems, SA (Single Action) mode requires manual cocking before the first shot but offers a very light pull, whereas DAO (Double Action Only) performs the entire cycle of cocking and releasing the firing mechanism with every single pull, resulting in a heavier trigger for added safety. The hybrid DA/SA mode combines both—the first shot has a heavy pull (as a defensive safety feature), while subsequent shots are light in SA mode thanks to the slide automatically cocking the hammer. Modern hammerless pistols dominate the market with the Striker-Fired system, where the trigger directly releases a firing pin (striker), along with its specific variant, Safe Action (used notably by Glock pistols), which integrates several automatic safety features for safe daily carry. Getting properly acquainted with these characteristics is key to the safe and accurate handling of any specific firearm.
Published 15.10.2024 / Ranger-Ka
DAO (Double Action Only): In DAO mode, each trigger pull is associated with a complete firing cycle. The trigger pulls the firing mechanism, then releases it and firing the round. After the shot, the trigger is reset and another trigger pull will again perform the complete firing cycle. This type of trigger is often used for safety purposes, as it requires a longer and heavier trigger pull.
SA (Single Action): In SA mode, the trigger is only associated with firing the round, without prior cocking of the firing mechanism. Single action trigger pistols require manual cocking of the firing mechanism before the first shot. After the first shot, the trigger returns to SA position until re-cocked.
DA/SA (Double Action/Single Action): These pistols have triggers that can operate in both modes. The first shot is in DAO mode - a heavier trigger pull and the firing mechanism is cocked. Then, once fired, the trigger switches to SA mode and subsequent shots are with a lighter pull, as the firing mechanism is already cocked.
Striker-Fired: Instead of the classic hammer and firing mechanism system, pistols with a Striker-Fired system use a fixed firing mechanism known as a „striker“. Attached to it is the trigger, and upon pulling the trigger, the striker is released, causing the shot. Many modern pistols, such as Glock, use this type of trigger.
Safe Action: This term is often associated with Glock pistols. Safe Action is actually a variation of the Striker-Fired system, which includes several safety mechanisms. It has a fixed firing mechanism (striker) and is designed to be safe for carrying.
Each type of trigger has its advantages and disadvantages, and it is important for the user to be familiar with the features and safety aspects of their pistol.
Would you like to try shooting with different triggers? Come to our shooting range in Prague. Our experienced instructors will teach you how to use different weapons from the very basics.