- 01: Introduction
- 02: History
- 03: Propellants, Firearms, and Ammunition Development
- 04: Modern Firearms Manufacture
- 05: Small Arms Ammunition
- 06: Evidence Handling Procedures
- 07: Equipment and Instrumentation
- 08: Examination of Firearms
- 09: Cartridge and Shotshell Examination
- 10: Characterization and Evaluation of Fired Projectiles
- 11: Bullet Comparison and Identification
- 12: Gunshot Residue and Distance Determination
- 13: Toolmark Identification
- 14: Communicating Results
- Resources
Trigger Systems
Home > Examination of Firearms > Handguns> Single and Multi-barreled Pistols > Trigger Systems
Colt 1911A1 Single action pistol
Single- or multibarrel pistols have trigger systems similar to revolvers.
Semiautomatic and full automatic pistols can have
- single-action trigger system,
- double-action trigger system,
- double-action-only trigger system.
Beretta model 92FS double action pistol
The single-action trigger is the most common system. The only function of the trigger is to discharge the firearm. The firearm cannot be cocked by use of the trigger. In firearms with an external hammer, the hammer may be manually cocked; in striker-fired weapons, the slide must be pulled to the rear and released to cock the firearm.
In the double-action system, the hammer can be at rest. Pulling the trigger cocks the hammer and fires the weapon. After the first shot is fired in double-action mode the remaining shots are fired in the single-action mode. This occurs because the firing cycle cocks the firearm after each shot until the hammer is manually placed at rest.
Taurus PT24/7 Double action only
The double-action-only (DAO) trigger system cocks and fires the firearm after each shot. The hammer returns to the rest position after each shot.
