University of Mississippi: How to Trace 3D Printed Guns for Forensic Analysis

Parker Riley Ball is a thesis student at the University of Mississippi, exploring some complex areas regarding 3D printing, outlined in ‘Development of a Dart-Mass Spectral Database for 3D Printed Firearm Polymers, and Airborne Mercury at Three Lakes in North Mississippi.’

The research study, centered around the uses of chemometric analysis, offers an interesting focus on weapons forensics, as Ball expounds on ways to collect data on 3D printed guns and analyze the forensic information, along with creating another ‘sampling’ device (unrelated to 3D printing) for measuring high levels of mercury in Grenada, Enid, and Sardis Lakes, all tributaries in Mississippi.

Ball discusses the ‘threat of 3D printed firearms’ at length, delving into a worldwide conversation that is controversial to say the least. His point in the thesis is that there is a need to track weapons, and 3D printed guns are currently manufactured and possessed completely off the grid—along with safeguarding features such as the ability to evade metal detectors—prompting the possibility that there may be legal necessity in the future to track such weapons and their ‘manufacturers.’ Amidst exploration of DART-MS, the study of 3D printed guns, and forensic research, Ball mainly performed data analysis and interpretation, with the rest left up to fellow graduate student, Oscar Black.

DART-MS stands for direct analysis in real time – mass spectrometry and allows for the collection of ‘mass spectra under ambient conditions.’ Samples can be taken quickly, and simply. And while this is already a well-known technique for taking samples, using them for 3D printed gun forensics is a novel concept.

“With a DART ion source, a gas, He or N2, passes through a discharge chamber where an electric current is applied to generate a glow discharge, producing excited neutral chemical species called metastables,” explains Ball. “A perforated electrode removes ions from the gas stream as it travels through a second chamber. In a third chamber, the gas is then heated, and the sample is ionized by reacting with the metastables and causing desorption.”

A schematic diagram of a DART ion system (Photo Credit: Dr. Chip Cody, as used in Ball’s Thesis Study)

The researchers can use DART with a spectrometer for pinpointing and identifying the unique makeup and pattern of each sample—in this case, a 3D printed polymer used to manufacture a weapon. Ball points out that the process does not harm a forensic sample in any way, meaning that evidence can be stored and explored further, as needed later in a trial. The DART-MS ‘fingerprint mass spectra’ also makes it useful in many other law enforcement applications like drug busts and other criminal activities requiring trace analysis.

A display including 30 of the plastic samples analyzed for this study.

As the researchers expanded their analysis efforts in conjunction with the DART-MS data, they were able to categorize samples by different polymers—followed by analysis of manufacturer and color. Ball emphasizes the importance of this work for law enforcement officials in the future as they could have greater luck in identifying crimes that are gun-related, requiring further evidence for trials and convictions. Samples were taken from 50 different types of 3D printing polymers, including PLA, ABS, PETG, nylon, and more.

While the second part of the study was not related to 3D printing, Ball was engaged in creating other analytical sampling devices, with the use of a Direct Mercury Analyzer. Find out more about that study and the mechanics of measuring mercury and toxicity levels here.

“The results from this study show strong potential for the classification and identification of unknown polymer evidence as the 3D-print polymer database continues to grow,” reports Ball in the conclusion of his thesis. Chemometric analysis of mass spectral data allowed for the successful classification of various 3D-print polymer samples, and thermal desorption techniques provided an even stronger basis for this classification. It is recommended that another full study be done in the future, with a focus on modifying the parameters used in the chemometric analysis of polymers for potentially stronger separation when generating PCA plots.”

Most of the 3D printing realm is uncharted territory, and as soon as the technology hit the mainstream, designers, engineers, and a multitude of creative users around the world were left to think up an infinite amount of ways to ‘change the world’ – and get in some trouble too. Weapons of course were high on the list for enthusiasts to take a stab at, whether in creating replicas for cosplay, creating gun designs and advocating, or bikers 3D printing guns in Australia to promote crime endeavors. It’s not likely that 3D printers are going to take over as the manufacturing technique of choice, but users are curious about what they can do, and weapons enthusiasts are often very passionate about their guns and different ways to construct, and enjoy them.

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Direct analysis of 3D-Print Polymer

Thermal Desorption unit coupled to DART source at the MS inlet