- 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
- Introduction
- Objectives
- AFTE Knowledge and Ability Factors
- Measurement, Standards, and Accuracy
- Weight, Force, and Their Measurement
- Dimensional Data and Measurement Tools
- Muzzle Velocity of Bullets
- Stereo and Comparison Microscopes
- Small Tools and Supplies
- Imaging Equipment
- Field Support Equipment
- Computer-Based Technologies
- Firing Facilities
- Selected Bibliography
- 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
Standard Trigger Weights
Home > Equipment and Instrumentation > Weight, Force, and Their Measurement > Standard Trigger Weights
Standard trigger pull weights (typically used by gunsmiths and the National Rifle Association) have been used by firearm examiners for many decades. They are effective when weight is carefully added in small increments. Excellent data is produced if the weights are suspended from a point on the trigger where the finger would rest and exert pressure to the rear.
Spring Gauges
The use of spring gauges is another traditional approach to measuring trigger pull. Firearm examiners required to perform testing outside of the laboratory prefer spring gauges because they are lightweight and easily calibrated.
Trigger pull gauge
Trigger pull gaugeMechanical Testers
High-precision
mechanical force gauge
A nondigital device, the mechanical trigger pull tester dates back to the 1970s. These can be mounted or handheld, depending on brand and design. Using various rod-type adapters, mechanical trigger pull testers can be used for both handguns and long guns. They are portable and can typically be calibrated by turning the bezel-type ring around the needle indicator. Peak values are recorded, but no digital information in the form of charts or graphs is provided for case documentation.
