Dimensional Data and Measurement Tools
Accurate dimensional measurements are essential in documenting many class characteristics of firearm/toolmark evidence. Until recently, scientific measurements were usually taken using a graphic analog format with a continuous display. Common examples include clocks (with hands), speedometers (with needles), and thermometers (containing an expanding fluid). Measuring tools provided analog readouts, such as the dial register on calipers and the vernier scale on micrometers. Today, these forms of measurement are being replaced by digital displays.
The instruments commonly used by examiners to gather dimensional data today include the following:
- Glass measuring reticule
- Electronic reticule
- Digital measuring equipment and software
- Machinist’s scale
- MP6 optical projector