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The theory behind “microstamping” is that firearms could be equipped with a firing pin or other internal firearm part that could imprint unique microscopic identification marks onto ammunition cartridge cases when the gun is fired. Each firearm and its corresponding markings would be entered into a computerized database accessible to law enforcement before leaving the factory. According to microstamping proponents, when police recover spent ammunition cases from a crime scene they could then examine the markings on the case and use that information to identify the firearm used in the incident and its owner.

This theory of microstamping does not survive real world application.

  •          Microstamping is inconsistent technology that greatly depends on the type of firearm it is applied to as well as the type of ammunition.[1][2][3] This has led researchers to call for further research before the technology is implemented.[4]
  •          One study found that microstamp markings were decipherable on just over half of expended cartridge cases.[5]
  •          Multiple tests have shown that microstamping technology can be defeated with common hand tools in under a minute.[6][7]
  •          Justice Department research shows criminals do not typically obtain firearms through retail sources, opting instead to acquire firearms through theft, “Off the street/underground market,” or “from a family member or friend, or as a gift.” Therefore, it is unlikely a found cartridge casing could be traced to a perpetrator.[8]
  •          The firearms industry estimated that “legislation requiring [microstamping] would raise the cost of legal firearms by well over $200 per gun for both law-abiding citizens and our law enforcement personnel.”[9]

Unworkable Technology

The most common form of proposed microstamping involves using a laser to etch a unique microscopic alpha-numeric code onto the tip of a firing pin. When a gun equipped with this technology is fired, the marked tip of the firing pin contacts the primer inside a cartridge casing. In theory, this action would leave legible markings on the primer that would facilitate identification of the firearm through recovered cartridge cases. In addition to alpha-numeric codes, researchers have experimented with outfitting firing pins with other forms of unique markings such as dot, gear, or radial bar codes.

In 2005, the California Policy Research Center funded a study at University of California, Davis to examine microstamping. The researchers equipped a variety of firearms with marked firing pins and tested them across a variety of ammunition.

Pointing out the inconsistency of the technology, the researchers noted, “The legibility and quality of the microstamped characters for all three encoding formats varied among the set of firearms tested.”[10] Moreover, the team determined that “Each brand of ammunition produced a different transfer rate.”[11]

The researchers found that the firing pin markings degraded over repeat use of the firearms.[12] The problem was particularly acute in testing a .22 rimfire semi-automatic pistol. Tested for 250 rounds, the researchers explained, “Over this test firing period, the alphanumeric characters showed extreme signs of degradation, so much so that no character dimensions were obtainable.”[13] Suggesting that a microstamping regime would necessitate even further gun controls, including the routine replacement of marked parts, the team acknowledged, “Due to the varying amounts of degradation seen on all of the firing pins, a determination of what constitutes a suitable lifespan of these characters needs to be developed.”[14]

At the time of the study, California was contemplating legislation to require microstamping technology in handguns. The UC Davis researchers rejected such a mandate, stating, “At the present time, therefore, because its forensic potential has yet to be fully assessed, a mandate for the implementation of this technology in all new semiautomatic handguns sold in the state of California is counter-indicated.”[15] Despite this, California Gov. Arnold Schwarzenegger signed microstamping legislation in 2007.[16]

In 2006, George G. Krivosta of the Suffolk County Crime Laboratory in New York published a study on the efficacy of microstamping in the Association of Firearm and Tool Mark Examiners (AFTE) Journal. For this test Krivosta employed one of the most widely used handguns in America, the 1911 semi-automatic pistol.

After firing 100 rounds, the spent cartridge cases were examined. On roughly half (46) of the cases one or more alpha-numeric symbol was undecipherable.[17] Moreover, the markings showed noticeable degradation after only one thousand rounds.[18]

Examining the technology for a 2008 document, the National Research Council of the National Academies determined, “substantial further research would be necessary to inform a thorough assessment of the viability of microstamping either gun parts or bullets.”[19]

Subsequent studies from Iowa State University confirm that the legibility of primer microstamp markings is inconsistent and highly dependent upon the firearm and ammunition used and the combination thereof.[20][21] In one of the studies, the researchers noted that testing made “clear that [microstamping] is not a perfect technology, even on optimized weapons.”[22]

Easily Defeated

A firing pin with identifiable markings can be replaced with an unmarked firing unmarked firing pin in as little as 25 seconds.[23] Violent criminals could opt to use revolvers – which do not automatically eject cartridge cases. Moreover, marked firing pins can be altered to remove the markings quickly and easily.

The UC Davis team examined marking defacement/obliteration using two methods “based upon common household tools and objects readily available to the general public.”[24] The first method consisted of rubbing a firing pin on a household sharpening stone for 30 seconds.[25] The second involved striking a marked firing pin with a ball peen hammer over the course of 15 seconds.[26] The researchers explained, “both defacement/obliteration methods demonstrated that the microcharacters could easily be intentionally destroyed…”[27]

Krivosta came to a similar conclusion in his ATFE Journal study. Describing an effort at intentional firing pin defacement with a sharpening stone, the researcher noted, “The entire process was easily accomplished in approximately one minute’s time with no special equipment or knowledge needed.”[28]

Ignores Criminal Firearm Acquisition

The theory behind microstamping relies on law enforcement’s ability to tie a microscopic marking left on a cartridge case to an individual firearm and then to a specific individual. The reality of criminal firearm acquisition renders this technology irrelevant.

Criminals who misuse firearms do not typically acquire guns through the traditional stream of commerce, and therefore are not subject to the recordkeeping requirements microstamping needs in order to function. A Department of Justice survey of state and federal inmates who possessed a firearm at the time of their offense determined that a mere 10 percent had acquired the firearm at a retail source. Rather, the vast majority (75 percent) of inmates acquired the firearm through theft, “Off the street/underground market,” or “from a family member or friend, or as a gift.”[29] According to the DOJ, “about 1.4 million guns, or an annual average of 232,400, were stolen during burglaries and other property crimes in the six-year period from 2005 through 2010.”[30]

Burdens Law-abiding Gun Owners

Since microstamping technology can be defeated in under a minute and criminals acquire guns in a manner inconsistent with the theory behind the technology, this gun control measure only serves to burden law-abiding gun owners.

Firearm industry trade group the National Shooting Sports Foundation has stated, “legislation requiring [microstamping] would raise the cost of legal firearms by well over $200 per gun for both law-abiding citizens and our law enforcement personnel.”[31]

Further, under a microstamping regime, criminals would be incentivized to acquire spent cartridge cases at shooting ranges in order to plant them at crime scenes in an attempt to throw the police off their tracks and confound prosecutors.[32] Such a scenario could have significant negative repercussions for a law-abiding shooter whose spent cases were used in such a manner.

[1] David Howett, Frederic A. Tulleners and Michael T. Beddow, What Microo Serialized Firing Pins Can Add to Firearm Identification in Forensic Science: How Viable are Micro-Marked Firing Pin Impressions as Evidence?, California Policy Research Center, University of California, 2008, at 9-10.

[2] L. Scott Chumbley, J. Kreiser, et. al., Clarity of Microstamped Identifiers as a Function of Primer Hardness and Type of Firearms Action, AFTE Journal Vol. 44 N. 2, Spring 2012, at 155.

[3] T. Grieve, L. Scott Chumbley, et. al., Gear Code Extraction from Microstamped Cartridges, AFTE Jounral Vol. 45 N. 1, Winter 2013, at 72-74.

[4] Howett at 11.

[5] George G. Krivosta, NanoTag Markings From Another Perspective, AFTE Journal Vol. 38 N. 1, Winter 2006, at 43.

[6] Id. at 43-44.

[7] Howett at 23-24.

[8] Mariel Alper & Lauren Glaze, Source and Use of Firearms Involved in Crimes: Survey of Prison Inmates, 2016, U.S. Department of Justice Bureau of Justice Statistics, 7 (2019), at 7.

[9] Microstamping Technology: Proven Flawed and Imprecise, National Shooting Sports Foundation, Feb. 2012, at 2.

[10] Howett at 9.

[11] Id. at 10.

[12] Id.

[13] Id. at 27.

[14] Id. at 10.

[15] Id. at 11.

[16] Schwarzenegger signs handgun “microstamp” bill, Reuters, October 14, 2007.

[17] Krivosta at 43.

[18] Id.

[19] Ballistic Imaging, National Research Council, 2008, at 271.

[20] Chumbley at 155.

[21] Grieve at 72-74.

[22] Chumbley at 155.

[23] Krivosta at 43.

[24] Howitt at 23.

[25] Id.

[26] Id. at 24.

[27] Id. at 10.

[28] Krivosta at 43.

[29] Alper at 7.

[30] Lynn Langton, Firearms Stolen during Household Burglaries and Other Property Crimes, 2005–2010, U.S. Department of Justice Bureau of Justice Statistics, November 2012, 1.

[31] National Shooting Sports Foundation at 2.

[32] David Muradyan, Firearm Microstamping: A “Bullet with a Name On It”, 39 McGeorge L. Rev. 616, 645-625.

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