1 

Reporting of Forensic 

Primer Gunshot Residue 

(pGSR) Analysis by 

Scanning Electron 

Microscopy/Energy 

Dispersive X-Ray 

Spectrometry (SEM/EDS) 

Gunshot Residue Subcommittee

Chemistry Scientific Area Committee

Organization of Scientific Area Committees (OSAC) for Forensic Science 
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Reporting of Forensic Primer Gunshot Residue (pGSR) 

Analysis by Scanning Electron Microscopy/Energy 

Dispersive X-Ray Spectrometry (SEM/EDS) 

Prepared by 

Gunshot Residue Subcommittee

Version:1.0 

March 2020 

Disclaimer: 

This document has been developed by the Gunshot Residue Subcommittee of the Organization 

of Scientific Area Committees (OSAC) for Forensic Science through a consensus process and 

proposed for further development through a Standard Developing Organization (SDO). This 

document is being made available so that the forensic science community and interested parties 

can consider the recommendations of the OSAC pertaining to applicable forensic science 

practices. The document was developed with input from experts in a broad array of forensic 

science disciplines as well as scientific research, measurement science, statistics, law, and 

policy. 

This document has not been published by a SDO. Its contents are subject to change during the 

standards development process. All interested groups or individuals are strongly encouraged to 

submit comments on this proposed document during the open comment period administered by 

ASTM International (www.astm.org). 
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Date: 8/21/2019

To: Subcommittee E30.01 

Tech Contact: David Freehling, dfreehling@ncdoj.gov, 919-582-8920

Work Item #: WK69622

Ballot Action: Proposed New ASTM Standard

Rationale: This document was created by the OSAC Gunshot Residue Subcommittee and reviewed by 

the OSAC Chemistry/Instrumental Analysis SAC and three resource committees.

Standard Practice for 

Reporting of Forensic Primer Gunshot Residue (pGSR) Analysis by Scanning 

Electron Microscopy/Energy Dispersive X-Ray Spectrometry (SEM/EDS)

1. Scope

1.1 This practice covers the scope of information to be contained in formal, written technical 

reports that expresses the results and conclusions of the scientific or technical expert with 

respect to pGSR analysis by SEM/EDS. 

1.2 This practice offers a set of instructions for performing one or more specific operations. This 

document cannot replace education or experience and should be used in conjunction with 

professional judgment. Not all aspects of this practice may be applicable in all circumstances. 

This ASTM standard is not intended to represent or replace the standard of care by which the 

adequacy of a given professional service must be judged, nor should this document be applied 

without consideration of a project’s many unique aspects. The word “Standard” in the title 

means only that the document has been approved through the ASTM consensus process.

1.3 This practice does not purport to address all of the safety concerns, if any, associated with its 

use. It is the responsibility of the user when applying this practice to establish appropriate safety 

and health practices and deter- mine the applicability of regulatory limitations prior to use.

1.4 This international standard was developed in accordance with internationally recognized 

principles on standardization established in the Decision on Principles for the Development of 

International Standards, Guides and Recommendations issued by the World Trade Organization 

Technical Barriers to Trade (TBT) Committee.

2. Referenced Documents

2.1 ASTM Standards:

2.1.1 E620 Practice for Reporting Opinions of Scientific or Technical Experts.

2.1.2 E1732 Terminology Relating to Forensic Science

2.1.3 E1588 Practice for Gunshot Residue Analysis by Scanning Electron 

Microscopy/Energy-Dispersive X-Ray Spectrometry.

2.2 SWGGSR Guide for Primer Gunshot Residue Analysis by Scanning Electron

Microscopy/Energy Dispersive X-Ray Spectrometry.
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3. Terminology

3.1 The terms listed below apply specifically to this document.

3.1.1 Background sample n - A recovered sample from a source that has not knowingly 

been exposed to pGSR that allows for threshold values to be calculated.

3.1.2 Candidate particles n - Particle(s) classified by the instrument software based on 

detection of appropriate constituent elements as potential pGSR.

3.1.3 Confirmed particles n - Particle(s) relocated, analyzed, and classified by the analyst 

as pGSR based on appropriate constituent elements and morphology.

3.1.4 Threshold n – A value, based on a comprehensive background sample study and 

data interpretation, below which the number of pGSR particles identified cannot be 

considered interpretable in associating the recovered sample with the discharge of a 

firearm or contact with a source of pGSR. 

4. Significance and Use

4.1 This practice is designed to be utilized by scientific or technical experts with regard to pGSR 

detection and analysis when issuing final reports. This practice does not include all topics 

specifically covered in the above referenced documents

5. Report

5.1 The report reflects the conclusions based on scientific results. These conclusions are based 

on the classification of particle data as defined in E1588 and the SWGGSR Guide. 

5.2 Pertinent Information. Satisfy the requirements of E620, Section 4.7, by listing:

5.2.1 The discipline specific technique. See 5.2.3

5.2.2 The general examinations conducted, including the generic class and type of 

instrumentation used. See 5.2.3

5.2.3 The methodology or procedure performed.

5.2.3.1 e.g. “Exhibit 1 was examined by SEM/EDS for the presence of pGSR 

particles based on elemental composition and morphology.”

5.2.4 It is recommended that the results of the examination include the quantity and 

elemental constituents of the confirmed pGSR particles present. State this information 

in the report using terms accepted by the pGSR scientific community. If using the terms 

“characteristic”, “consistent”, and “commonly associated” with pGSR in lieu of reporting 

elemental constituents, define these terms in the report, appendix, or within supporting 

records (25). .

5.2.5 For laboratories that use threshold values, state that value in the written report.
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5.2.6 Regarding the estimated uncertainty of measurement in pGSR, several factors 

have been identified that affect the number of pGSR particles present on a recovered 

sample. Some of these factors are listed in 5.6.1 through 5.6.3.

5.3 Descriptive Information. Meet the requirements of E620, Section 4.7, and, in addition,

5.3.1 If errors are detected in an issued report, issue an amended report that contains 

the reasons for the amendments. Indicate that it is an amended report and include the 

date of the original report.

5.3.2 Indicate on the report if the report is a supplemental report and include the date 

of the original report.

5.4 Report Examples. Meet the requirements of E620, Section 4.9. The examples listed below 

do not purport to show all possible reporting styles and can be subject to modifications.

5.4.1 Results based on confirmed particles detected on the recovered sample, either 

consistent with, or characteristic of pGSR.

5.4.1.1 (Numerical Value) particles characteristic of pGSR and/or (numerical value) 

particles consistent with pGSR were confirmed on the (sample source).

5.4.1.2 (Numerical Value) particles containing lead, barium, and antimony were 

confirmed on the (sample source). 

5.4.1.3 At least (threshold value) particles characteristic of pGSR were confirmed 

on the (sample source). 1

5.4.1.4 (Numerical value) particles containing (elemental constituents) were 

confirmed on the (sample source).

5.4.2 Results based on the absence of confirmed particles detected on the recovered 

sample, either consistent with, or characteristic of pGSR.

5.4.2.1 No characteristic pGSR particles were detected on the (sample source).

5.4.2.2 No particles confirmed as either characteristic of or consistent with pGSR 

were detected on the (sample source).

5.4.2.3 (Numerical value) particles characteristic of pGSR were confirmed but 

were below the established threshold level to be considered interpretable 

based upon previously conducted background studies.1

5.4.2.4 (Sample source) contained particles characteristic of background 

samples.

 

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For use by laboratories with an established threshold value. Laboratories must be able to provide 

the supporting background sample study and data interpretation which the threshold value is based 

on, if requested. An Appendix to the report can be used to detail the specific number and 

classification of particles detected.
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5.4.3 Inconclusive/indeterminate results indicate to the reader that no conclusion can 

be drawn based on the analytical data obtained. This result could be due to, but is not 

limited to contamination, unusual particle populations, and/or unusual elements 

present in particles. Further testing could be warranted for a more definitive conclusion 

to be reached (25).

5.4.3.1 The particles on the (sample source) do not allow the analyst to form an 

opinion, due to ______.

5.4.3.2 The presence of [atypical element(s)] in combination with lead, barium, 

and antimony is uncommon. Therefore, no conclusions can be reached 

regarding this sample unless a spent cartridge is submitted for comparison.

5.4.3.3 Characteristic pGSR particles were detected on the negative control. No 

conclusion can be reached regarding the particles recovered from the (sample 

source).

5.5 Conclusions and limitations

5.5.1 Conclusions are drawn from the identification of characteristic pGSR 

particles on a recovered sample from a person. Include wording clarifying that 

the person discharged a firearm, was in the vicinity of a firearm discharge, or

came in contact with something that had pGSR on it. The number of confirmed 

particles cannot be used to determine which of these scenarios actually 

occurred.

5.5.1.1 The subject discharged a firearm, handled a discharged firearm, 

was in proximity to a discharged firearm, or contacted an object with 

pGSR on it.

5.5.1.2 pGSR can be deposited on the hands by circumstances such as: 

discharging a firearm, handling a firearm, being in proximity to the 

discharge of a firearm, or coming into contact with an object or person(s) 

that has pGSR on it. 

5.5.2 Conclusions are drawn from the identification of pGSR particles on a 

recovered sample from an inanimate object. Address the potential that at some 

time in the history of the item, it was in the vicinity of a firearm during discharge 

or had pGSR transferred to it.

5.5.2.1 (Sample source) contacted a pGSR related item or was in proximity 

to a discharged firearm.

5.5.2.2 The (sample source) of the (sample source)/the (sample source) 

belonging to (sample source) could have been in the vicinity of a 

discharged firearm or had pGSR transferred to it.

5.5.3 Conclusions are drawn from the identification of consistent pGSR particles 

on a recovered sample from a person. Include wording clarifying that the 
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person discharged a firearm, was in the vicinity of a firearm during discharge, or 

was exposed to a source of pGSR. Additionally, state that the particles could 

have originated from a non-firearm source.

5.5.3.1 Consistent pGSR can be deposited on the hands by circumstances 

such as: discharging a firearm, handling a firearm, being in the proximity 

to the discharge of a firearm, coming into contact with an object that has 

pGSR on it, or received from a non-firearm source.

5.5.4 Conclusions are drawn from recovered samples in which pGSR evidence is 

absent from the sample source. Include wording clarifying that the sample

source could have been exposed to pGSR but the pGSR particles were not 

present when the recovered sample was collected or the sample source could 

have no association with the discharge of a firearm. Do not confuse the 

absence of pGSR particles with inconclusive interpretations. The absence of 

pGSR particles can support the theory that an item was not exposed to pGSR.

5.5.4.1 There is no indication that the (sample source) has any association 

with the discharge of a firearm. However, the absence of pGSR particles is 

not corroboration that a person did not discharge a firearm. If (sample 

source) did discharge a firearm, then pGSR particles were not deposited, 

were removed by activity, or were not detected.

5.5.4.2 There is no indication that the (sample source) came into contact 

with pGSR or was in the vicinity of a firearm during discharge. If (sample 

source) was, then the pGSR was not deposited, not detected, or removed.

5.5.5 No conclusions can be drawn from a sample with inconclusive results that 

are based on the analytical data.

5.5.5.1 No determination can be made from the (sample source) (, for the 

following reason(s) _____). Submission of appropriate additional 

evidence could yield conclusive findings.

5.5.6 No conclusions can be drawn from the identification of particles that are 

commonly associated with pGSR. This includes lead, barium, or antimony 

particles found in isolation in the absence of characteristic and consistent pGSR 

particles. An exception to this might include finding high levels of small spherical 

lead particles that can be shown to originate from bullet or pellet debris or from 

a primer comprised of a lead-based compound only, supported by analysis of a 

reference sample. In most circumstances, however, such particles shall not be 

reported as potentially having originated from the discharge of a firearm.

5.5.7 Include the details of the elements and combinations of elements that are 

being considered in making a conclusion if a comparison of results to known 

ammunition is conducted. Indicate these particle types could originate from 

other ammunitions, unless the ammunition in this case is manufactured for a 

unique application, such as ammunition with taggant elements.
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5.5.8 An explanatory statement or page can accompany the report if it assists 

the reader in understanding the information provided. Examples of the 

statements are listed below.

5.5.8.1 Microscopic particles containing any combination of lead, barium, 

or antimony are known to be associated with pGSR. If possible the known 

firearm and ammunition should be submitted if further testing is desired.

5.5.8.2 The absence of detected pGSR particles does not preclude the 

association of (sample source) with the discharge of a firearm.

5.5.8.3 Victims of a gunshot-related injury can have particles of pGSR 

present.

5.5.8.4 Published studies have shown that residue from certain fireworks, 

brake pads, air bag detonators, or percussion grenades can contain pGSRlike particles. However, there are typically elemental indicators that 

exclude these particles from being identified as pGSR.

5.5.8.5 Law enforcement officers, active duty military personnel, hunters, 

or firearm enthusiasts could be a source of pGSR.

5.5.8.6 Secondary and tertiary transfers are possible. However, the 

frequency of these occurrences is currently unknown. 

5.5.8.7 pGSR is not specific to a particular firearm or ammunition. 

5.6 Remarks/Additional Information that can be included in the report. Specific 

references for a topic are listed in Section 6.

5.6.1 Primary Transfer Considerations: Factors that can influence the number of 

particles deposited or influence the lack of particles if known that the subject 

discharged a firearm.

5.6.1.1 Formation: (17, 21, 22, 24, 26, 27, 30)

5.6.1.1.1 Type of firearm.

5.6.1.1.2 Physical condition of firearm.

5.6.1.1.3 5.6.1.1.3 Caliber of firearm.

5.6.1.1.4 5.6.1.1.4 Type of ammunition.

5.6.1.2 Deposition: (1-4, 10, 11, 16, 20, 23, 27, 28)

5.6.1.2.1 Amount of pGSR present.

5.6.1.2.2 Number of rounds fired.

5.6.1.2.3 Proximity to a discharging firearm.

5.6.1.2.4 Time of discharge to time of collection.

5.6.1.2.5 Physical barrier preventing deposition of pGSR 

(gloves, hands in pockets, etc.)
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5.6.1.2.6 Environmental conditions (wind, rain, etc.).

5.6.1.3 Retention: (11, 18, 19, 27, 28)

5.6.1.3.1 Washing/wiping of hands.

5.6.1.3.2 Excessive perspiration.

5.6.1.3.3 Blood on hands.

5.6.1.3.4 Activity of subject.

5.6.1.4 Collection: (8, 29)

5.6.1.4.1 Condition of sampling surface being tested.

5.6.1.4.2 Proper training of collection personnel.

5.6.1.5 Analysis Factors

5.6.1.5.1 As the test methods do not represent an exhaustive 

search of the sample, it is recognized that not all 

particles will be detected.

5.6.1.5.2 Limit of detection.

5.6.1.5.3 Performance of SEM/EDS system. 

5.6.1.5.4 Presence of material on adhesive surface of 

sampling device that is obscuring pGSR.

5.6.2 Secondary Transfer Considerations: Factors that can influence the number 

of particles deposited or influence the lack of particles if known that the 

subject did not discharge a firearm (5-7, 12, 13, 15, 25).

5.6.2.1 Being in physical contact with an individual who has recently 

discharged a firearm.

5.6.2.2 Being in physical contact with an inanimate object that has 

recently been in contact with a discharged firearm.

5.6.2.3 Wearing an item of clothing that has been in proximity to or in 

contact with a discharged firearm.

5.6.3 Tertiary Transfer Considerations: Factors that can influence the number of 

particles deposited or influence the lack of particles if known that the 

subject did not discharge a firearm (14, 15).

5.6.3.1 Being in physical contact with an inanimate surface that was 

recently in contact with an individual who discharged a firearm.

5.6.3.2 Being in physical contact with an individual who was recently in 

contact with an individual who discharged a firearm.

6.0 References

(1) Andrasko J., et al., A Simple Method for Collection of Gunshot Residues from Clothing,” J 

Forensic Sci Soc, Vol. 31, 1991, pp. 321-330. 
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(2) Basu S, Boone CE, Denio DJ, Miazga RA., Fundamental Studies of Gunshot Residue 

Deposition by Glue-Lift. J Forensic Sci 1997; 42 (4):571-81. 

(3) Brozek-Mucha Z., Distribution and Properties of Gunshot Residue Originating from a 

Luger 9 mm Ammunition in the Vicinity of the Shooting Gun. Forensic Sci Int, Vol. 183, 

2009, pp. 33-44. 

(4) Brozek-Mucha Z., Chemical and Morphological Study of Gunshot Residue Persisting on 

the Shooter by Means of Scanning Electron Microscopy and Energy Dispersive X-Ray 

Spectrometry. Microscopy and Microanalysis, Vol. 17, 2011, pp. 972–982. 

(5) Brozek-Mucha Z., On the Prevalence of Gunshot Residue in Selected Populations – An 

Empirical Study Performed with SEM-EDX Analysis. Forensic Sci Int 2014; 237:46-52. 

(6) Bull PA., et al., The Transfer and persistence of Trace Particulates: Experimental Studies 

using Clothing Fabrics. Sci Justice 2006; 46 (3):185-95. 

(7) Charles S, Geusens N., A Study of the Potential Risk of Gunshot Residue Transfer from 

Special Units of the Police to Arrested Suspects. Forensic Sci Int 2012; 216 (1-3):78-81. 

(8) Charles S, Lannoy M, Geusens N. Influence of the Type of Fabric on the Collection 

Efficiency of Gunshot Residues. Forensic Sci Int 2013; 228 (1):42-6. 

(9) Cook M., Gunshot Residue Contamination of the Hands of Police Officers Following Startof-shift Handling of their Firearm. Forensic Sci Int 2016; 269:56-62. 

(10) Cornelis R, Timperman J. Gunfire Detection Method Based on Sb, Ba, Pb, and Hg Deposits 

on Hands. Evaluation of the Credibility of the Test. Med Sci Law 1974; 14(2):98-116. 

(11) Douse M, Smith RN. Trace Analysis of Explosives and Firearm Discharge Residues in the 

Metropolitan Police Forensic Science Laboratory. J Energy Materials 1986; 4(1-4):169-86. 

(12) Fojtasek L., et al., Distribution of GSR Particles in the Surroundings of Shooting Pistol. 

Forensic Sci Int 2003 132(2):99-105. 

(13) French J, Morgan R, Davy J., The Secondary Transfer of Gunshot Residue: An 

Experimental Investigation Carried out with SEM-EDX Analysis. X-Ray Spectrum. 2014; 

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(14) French J, Morgan R. An Experimental Investigation of the Indirect Transfer and 

Deposition of Gunshot Residue: Further Studies Carried out with SEM-EDA analysis. 

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(15) French J, Morgan RM, Baxendell P, Bull PA. Multiple Transfers of Particulates and their 

Dissemination within Contact Networks. Sci Justice 2012; 52(1):33-41. 
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(16) Gerard RV, McVicar MJ, Linday E, Randall ED, Harvey E. The Long-range Deposition of 

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(17) Heard BJ. Handbook of Firearms and Ballistics: Examining and Interpreting Forensic 

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(18) Jalanti T., et al., The Persistence of Gunshot Residue on Shooters' Hands, Sci Justice;

39(1); 48-52. 

(19) Kilty J., Activity After Shooting and Its Effect on the Retention of Primer Residue, J 

Forensic Sci 1975; 20(2): 219-30. 

(20) Lopez-Lopez M, Delgado JJ, Garcia-Ruiz. Analysis of Macroscopic Gunshot Residues by 

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(21) Meng H, Caddy B. Gunshot Residue Analysis – A Review. J. Forensic Sci1997:42(4):553-70. 

(22) Romolo FS, Margot P. Identification of Gunshot Residue: A Critical Review. Forensic Sci 

Int 2001:119:195-211. 

(23) Schlesinger HL, Lukens HR, Guinn VP, Hackleman RP, Korts RF. Special Report on Gunshot 

Residues Measured by Neutron Activation Analysis. USAEC Report GA-9829. San Diego, 

CA: Gulf Atomic General, 1970. 

(24) Schwoeble S. and Exline D., Current Methods in GSR Analysis, Boca Raton, FL CRC Press, 

2000.

(25) SWGGSR Guide for Primer Gunshot Residue Analysis by Scanning Electron 

Microscopy/Energy Dispersive X-Ray Spectrometry (2013) 

https://www.swggsr.org/publications

(26) Shaffer DK, Yi K. A Comparison of Particle Transfer Efficiencies of Two Collection Methods

for the Identification of Gunshot Residue on Fabric Surfaces Using Scanning Electron 

Microscopy-Energy Dispersive Spectrometry. Scanning. 1999 Mar-Apr; 21(2):99-100. 

(27) Wallace JS. Chemical Analysis of Firearms, Ammunition, and Gunshot Residue. Boca 

Raton, FL: CRC Press; 2008. Chapter 17: Properties of Firearm Discharge Residue: 123-33. 

(28) Wolten GM, Nesbitt RS, Calloway AR, Loper GL, Ford PF. Final Report on Particle Analysis 

for Gunshot Residue Detection, Report ATR-77(7915) Segundo, CA: The Aerospace Corp. 

1977. 

(29) Zech WD, Kneubuhl B, Thali M, Boliger S. Pistol Thrown to the Ground after Fatal Selfinflicted Gunshot Wound to the Chest. J Forensic Leg Med 2011; 18 (2):88-90. 

(30) Zeichner A., et al., Collection Efficiency of Gunshot Residue (GSR) Particles from Hair and 

Hands Using Double-Sided Adhesive Tape, Journal of Forensic Sciences, Vol. 38, No 3, 

1993, pp. 571-584.
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(31) Zeichner A, Levin N, Dvorachek M. Gunshot Residue Particles Formed by Using 

Ammunitions that have Mercury Based Primers. J Forensic Sci 1992; 37(6):1567-73.