- 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
Calibration
Home > Equipment and Instrumentation > Weight, Force, and Their Measurement > Calibration
A set of precision weights for
balance calibration
Instrument calibration involves determining the difference (if any) between the output reading produced and a known standard, and remedying that difference. For digital scales, this means ensuring that the microprocessor correctly relates the amplified digital output signal to a standard weight. Manufacturers of the digital scales most commonly used by firearms examiners provide both known weights (usually not NIST traceable) and detailed but simple instructions for calibration. Calibration takes only a few minutes to perform but is necessary to ensure the accuracy of results.
Changes in heat and humidity as well as unlevel working surfaces can affect the readings of a digital scale by slightly shifting the zero point. Rough usage and power surges can cause harm to a digital scale.
Calibration of a digital scale is simple to perform. However, NIST traceable weights for calibration are a requirement of ISO/IEC 17025:2005 accredited laboratories.
