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Taking Measure

Just a Standard Blog

Xiaoyu Alan Zheng

Xiaoyu Alan Zheng is a mechanical engineer in the NIST Surface and Nanostructure Metrology Group. His research is focused on objective measurements and analysis of 2-D/3-D ballistics toolmarks. He is currently a member of the Subcommittee on Firearms & Toolmarks in the NIST OSAC as well as a technical adviser for AFTE.

Building a Firearms Toolmark Database

Although they are mass produced, every firearm is unique, and when fired, they leave unique markings called toolmarks on the bullet and cartridge casing. Law