Forensic marks on a cartridge case

Animation explaining the firearm parts that leave marks on a fired cartridge case.
Client
NIST
Year
2022
Type
animation / explanatory diagram
Field
forensic science / firearms and toolmarks
Links
NIST firearms and toolmarks
Description
Animation and cartridge cutaway explaining the marks forensic experts examine on fired cartridge cases.

Context

Forensic firearm examiners compare marks left on fired cartridge cases. NIST's explainer describes four common sources of these marks: the firing pin, breech face, extractor, and ejector.

Approach

I made an animation showing where each mark comes from as a cartridge moves through a firearm. The sequence uses cutaway views and highlighted parts so viewers can connect each contact point with the mark it leaves behind.

I also built a Blender texture rig to control the cartridge-case marks during animation, and made a small cutaway illustration showing the parts of a cartridge.

Process

Cutaway illustration labeling the casing, primer, powder, bullet, and full cartridge.
Blender texture rig used to control firing-pin, breech-face, extractor, and ejector marks.