The science of projectiles and firearms is defined as ‘ballistics’ and it can be divided into three distinct categories: internal, external and terminal.

Exit wounds – as we have already mentioned – are usually larger than the entrance wound and this is because as the round moves through the body of the victim it slows down and explodes within the tissue and surrounding muscle.

If investigators recover bullets or cartridge cases from a crime scene, forensic examiners can test-fire a suspect’s gun to see if it produces ballistic fingerprints that match the evidence. A fired bullet with rifling impressions from the barrel of a gun (left).

Study finds less than 1.2 percent error rate in matching bullets fired from Glock semiautomatic pistol barrels to the actual firearm. When most firearms are fired, these tool marks are transferred to the discharged (“spent”) cartridge casings and bullets. …

If police can find a potential weapon used in a crime, forensic experts can then analyse the striations on the bullet, which occurred during its passage through the gun. This allows forensic scientists to run test bullets through the gun to compare the resulting marks with the recovered bullets.

Once seen as crime scene detritus, bullets and ejected shell casings — which have unique sets of scratches, grooves and dents — are recognized these days as vital pieces of evidence.

One of the biggest problems in making an identification is that few evidence bullets are submitted intact. Most are badly distorted, wiped and/or fragmented.

Bore

Forensic ballistics involves the examination of evidence from firearms that may have been used in a crime. If investigators recover bullets from a crime scene, forensic examiners can test-fire a suspect’s gun, then compare the marks on the crime scene bullet to marks on the test-fired bullet.

Impression evidence is created when two objects come in contact with enough force to cause an “impression.” Typically impression evidence is either two-dimensional — such as a fingerprint — or three-dimensional — such as the marks on a bullet caused by the barrel of a firearm.

• Types Impression Evidence.
• Shoe Impressions.
• Historical Case.
• Use Caution.
• Preservation and Documentation.
• Tire Impressions.
• Glove Prints.
• Tool Mark Impressions.

Shoeprints, tool marks, tire tracks, bite marks, and marks on a fired bullet are several examples of impression evidence. Impressions may be found in or on many different types of materials.

There are two main types of toolmarks that can be distinguished: slipped and molded impressions. The slipped impression occurs as the tool drags or slides across the surface.

Impressions fall into three basic categories: patent, latent, and plastic.

There are three major categories of tool marks: indentations marks, abrasion marks, and cutting marks.

On painted surfaces bearing a toolmark, sample scrapings of the paint should be collected from areas around the toolmark for submission to the Laboratory. Paint may not be readily seen adhering to the tool; however, microscopic examination of the tool may reveal minute particles having evidentiary value.

Forensically significant toolmarks identified at crime scenes can be compared against suspected tools or firearms. Such evidence can link the marks to a class of tools or firearm or, if sufficient markings are present, to one specific tool or firearm.

The NIST Ballistics Toolmark Research Database is an open-access research database of bullet and cartridge case toolmark data. This database will: foster the development and validation of measurement methods, algorithms, metrics, and quantitative confidence limits for objective firearm identification.

Tool marks are considered to be circumstantial evidence. If a tool mark impression is matched to a specific tool, then the owner of that tool must have been at the crime scene. Pry bar and crowbar marks cannot be distinguished from each other.

National Integrated Ballistics Information Network

Toolmark identification is a forensic science discipline that has as its primary concern the determination of whether or not a toolmark was produced by a particular tool. This determination is based on the class and individual marks in a given toolmark, which are products of the manufacturing process.

Toolmark Identification is a forensic science discipline that is typically referred to as Firearm and Toolmark Identification because a firearm is considered a specialized tool and the most common tool examined by forensic science laboratories.

$55,000 per year

-It can be both class and individual, but mostly individual. The individual striations that are found on a bullet are found when a specific gun shoots it out. How can striations help to link a bullet to a gun?

An investigator would not pick up a weapon by its barrel with a pencil or stick in order to protect fingerprints because this may disturb powder deposits, rust, or dirt lodged in the barrel, and consequently may alter the striation markings on test-fired bullets.