 The firearms and toolmark unit conducts many different types of examinations. They do mechanical function checks on firearms to see if they're working properly. This includes test firing of firearms for bullet and cartridge case specimens for possible comparison with evidence. Gunpowder pattern testing, also known as proximity testing, to determine the distance a firearm was from a victim. Microscopic comparison of fired bullets and cartridge cases to determine if they were fired by a specific firearm. Microscopic comparison of tools, like screwdrivers, wire cutters, or punches, to tool marks or physical matches left at a crime scene. And restoration of obscured serial numbers on firearms and other objects using specialized assets. The firearms and toolmark unit also utilizes the National Integrated Ballistic Information Network, or NIBIN, database entries and examinations. NIBIN captures digital images and 3D renderings of unique marks on fired cartridge cases recovered from crime scenes or test fired on our forensic firearms range. It compares these images to others in the NIBIN database to see if they match any previous shooting incidents. Any potential associations found using the database are confirmed via traditional microscopic comparisons. This is done using our Leica comparison microscope, which is the primary instrument used by a firearm and toolmark examiner. This microscope allows for the side-by-side comparison of evidence at up to 60 times magnification. The firearms and toolmark unit maintains a large firearm reference collection, which serves an important role in training and research. It provides a reference for serial number appearance, composition and location, and is a source for replacement parts when they're needed to make damaged or disassembled evidence firearms operable. The final stop on our tour of the firearms and toolmark unit is the forensic firearms range. This 75-foot long space is used to safely test firearms when no bullet recovery is necessary. When a test bullet is needed, the bullet recovery tank is used. This specialized water tank allows for the collection of fired bullets that maintain their original, undamaged condition.