1. Introduction

During the sniper shootings in the Washington D.C.area in October 2002, it became clear that some of thekey evidence linking the shootings were the bullet frag-ments recovered from the crime scenes. This drewattention to the science and technology of ballisticsidentification, and to a system known as the NationalIntegrated Ballistics Information Network (NIBIN), inwhich images of bullets and casings collected fromcrime scenes are matched against a database of previ-ously recorded images [1].

Bullets and casings when fired or ejected from gunspick up characteristic signatures, which are unique tothe weapon. Striations on the bullet are caused by itspassage through the gun barrel. Marks on the casing arecaused by impact with the firing pin, breech face andejector. By analyzing these signatures, firearm examin-ers can connect a firearm to criminal acts. In the early1990s, the IBIS2 (Integrated Ballistics IdentificationSystem) and the DRUGFIRE system were establishedfor this purpose in laboratories of the Bureau of

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[J. Res. Natl. Inst. Stand. Technol. 109, 533-542 (2004)]

SRM 2460/2461 Standard Bullets andCasings Project

Volume 109 Number 6 November-December 2004

J. Song, E. Whitenton, D.Kelley, R. Clary, L. Ma1 andS. Ballou

National Institute of Standardsand Technology,Gaithersburg, MD 20899

and

M. Ols

Bureau of Alcohol, Tobacco andFirearms (ATF),Ammendale, MD 20705

jun-feng.song@nist.gov

The National Institute of Standards andTechnology Standard Reference Material(SRM) 2460/2461 standard bullets andcasings project will provide support tofirearms examiners and to the NationalIntegrated Ballistics Information Network(NIBIN) in the United States. The SRMbullet is designed as both a virtual and aphysical bullet profile signature standard.The virtual standard is a set of six digi-tized bullet profile signatures originallytraced from six master bullets fired at theBureau of Alcohol, Tobacco and Firearms(ATF) and the Federal Bureau ofInvestigation (FBI). By using the virtualsignature standard to control the tool pathon a numerically controlled diamond turn-ing machine, 40 SRM bullets were pro-duced. A profile signature measurementsystem was established for the SRM bul-lets. The profile signature differences arequantified by the maximum of the cross

correlation function and by the signaturedifference between pairs of compared pro-file signatures measured on different SRMbullets. Initial measurement results showedhigh reproducibility for both the measure-ment system and production process of theSRM bullets. A traceability scheme hasbeen proposed to establish the measure-ment traceability for nationwide bullet sig-nature measurements to NIST, ATF andFBI. Prototype SRM casings have alsobeen developed.

Key words: ballistics; bullet signature;standard reference material; SRM; stan-dard bullet; standard casing.

Accepted: November 24, 2004

Available online: http://www.nist.gov/jres

1 Guest Researcher, Catholic University of America, Washington,DC 20064.

2 Certain commercial equipment, instruments, or materials are iden-tified in this paper to foster understanding. Such identification doesnot imply recommendation or endorsement by NIST, nor does itimply that the materials or equipment identified are necessarily thebest available for the purpose.

Alcohol, Tobacco and Firearms (ATF) and the FederalBureau of Investigation (FBI), respectively [1-3]. Bothsystems were based on image capture, image analysisand database techniques. In 1998, ATF and FBI initiat-ed a joint project to establish the National IntegratedBallistics Information Network (NIBIN) [1-3]. InDecember 2002, after a nearly 2 year effort, computerspecialists finished installing IBIS workstations intothe last of the 233 U.S. crime labs slated to be on theNIBIN [1].

The IBIS is a computerized bullet and casing signa-ture comparison system. It consists of a data acquisitionstation and a signature analysis station. The data acqui-sition system uses an optical microscope which cap-tures an image of the bullet or casing surface in a cam-era. The correlation algorithm of the signature analysisstation produces scores based on the degree of similar-ity between the reference image and each specimen,thus providing a list of high confidence candidates sort-ed in either ascending or descending order. For bulletimage signature comparisons, the IBIS score may becalculated between a single pair of land images orbetween two sets of images containing, say, six landseach. In order to ensure that both the optical-imagingstation and the image-analyzing station of the ballisticsidentification systems work correctly, bullets are firedand collected at both the ATF National LaboratoryCenter and the FBI Central Laboratory under a stan-dardized firing procedure. The bullets are intended formeasurement quality control of IBIS systems and arecalled QA (Quality Assurance) bullets. However, it hasbeen found that the bullet signatures of the QA bullets,even fired from the same gun, showed significant dif-ferences, and that the signatures change over time. InDecember 1995, ATF firearm examiner R. Thompsonwrote to the Director of the Office of Law EnforcementStandards (OLES) at the National Institute of Standardsand Technology, outlining the concept of mass-produc-ing quality assurance standards for bullets and casings.These bullets and casings would bear such a highdegree of reproducible and recognized patterns of bul-let signatures, that they could be tested at different IBISlocations, which would then maintain scores within arelative consistency and rank.

In response, through OLES funding obtained fromthe National Institute of Justice (NIJ), the PrecisionEngineering Division at NIST started a project on SRM(Standard Reference Material) 2460/2461 standard bul-lets and casings. In the following sections, we discussthe design and manufacture of the SRM bullets in Sec.2, introduce a bullet profile signature measurement sys-tem and initial measurement results in Sec. 3, and pro-

pose a traceability system for nationwide ballisticsmeasurements in Sec. 4. The prototype SRM casingsand initial test results are described in Sec. 5.

2. A Virtual/Physical Bullet ProfileSignature Standard

2.1 Basic Technical Requirements

According to the VIM (International Vocabulary ofBasic and General Terms in Metrology) [4], a referencematerial is defined as:

material or substance one or more of whose prop-erty values are sufficiently homogeneous and wellestablished to be used for the calibration of anapparatus, the assessment of a measurementmethod, or for assigning values to materials.

With this definition in mind, we have developed tech-nical requirements for the standard bullets [5]:

• Real bullet surface characteristics: As a referencestandard for the ballistics identification system, thebullet signature must be obtained from real bullets,and duplicated on the surface of the physical stan-dards, the SRM bullets, with high fidelity. The shape,size, material and color of the physical standard bul-lets should be as close as possible to those of real bul-lets.

• Repeatability and reproducibility: As a measurementstandard, the profile signatures on the SRM bulletsmust show such a high degree of repeatability andreproducibility that when these SRM bullets are dis-tributed for checking instrument calibrations, they allplay the same function as a single SRM bullet.Repeatability here means that the profile signaturesare essentially identical over different SRM bulletsproduced at the same time. Reproducibility meansthat the profile signatures are highly uniform amongdifferent SRM bullets produced over time.

• Measurement traceability: The profile signaturemeasurements for SRM bullets performed at NISTSurface Calibration Laboratory must be traceable tothe SI unit of length. By using these SRM bullets,bullet image signature measurements using opticaltechniques performed at local forensic laboratoriescan be traced to the ATF National Laboratory Centerand to the FBI Central Laboratory.

• Information technology: It is advantageous to basethe SRM bullets on information technology. Then the

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digitized profile signatures may be stored in a NISTcomputer, and used to produce and re-produce theidentical SRM bullets at anytime.

Considering the above technical requirements, theSRM 2460 standard bullet is designed as both a virtualand a physical bullet signature standard described in thefollowing.

2.2 Establishment of a Virtual Bullet SignatureStandard

The SRM bullets are designed with six land impres-sions. The virtual standard of the bullet profile signa-tures is a set of six digitized profile signatures stored ina NIST computer. In 2000, the ATF NationalLaboratory Center and the FBI Central Laboratory pro-vided NIST with a total of six master bullets, three fromeach agency. They were fired from different guns understandardized firing conditions. These master bulletsunderwent profile measurements at the NIST SurfaceCalibration Laboratory using a commercial stylusinstrument. Each bullet was traced on one land. Theresulting set of six digitized bullet profile signatureswas stored in a NIST computer as the virtual standardfor both the fabrication and for the control of measure-ments of the SRM bullets [5].

2.3 Manufacture of the Physical Standard—SRM2460 Standard Bullets

The Precision Engineering Division at NIST has along history of developing surface roughness speci-mens [6-9]. In 1998, a virtual/physical random profilesurface roughness standard was developed at NISTusing a numerically controlled (NC) diamond turningprocess [9]. Based on the same NC diamond turningtechnique for manufacturing random profile roughnessspecimens, two prototype standard bullets were devel-oped in April 1998 [10,11]. From 1998 to 2001, testswere conducted on these prototype standard bullets.The results showed high uniformity and reproducibilityfor profile signatures [10,11]. Comments on them werecollected from firearm examiners at ATF and FBI.From this information, improvements were made toboth the design and manufacturing process for SRM2460 standard bullets. In January 2002, 20 SRM bulletswere produced and in June 2003, another 20 bulletswere produced.

Because the SRM bullets are manufactured by NCdiamond turning the profile signature onto the bulletsurface, bright acid copper is the preferred material forelectroforming the substrate. The deposit is electroplat-ed onto copper cylinders, which are then used for thediamond turning process [12]. Figure 1 shows the man-ufacturing setup on a numerically controlled diamondturning machine at the NIST Instrument Shop. The set

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Fig. 1. Manufacturing setup for SRM 2460 standard bullets: One of twenty SRM bullets (1) wascut by a diamond tool (2). Each bullet was fastened to a cylinder (3), which was mounted on a“V” block (4) set on an aluminum wheel (5). 20 SRM bullets were manufactured at the sametime.

of standard bullets (1) were cut by a diamond tool (2).The bullets were fastened to cylinders (3), which weremounted on “V” blocks (4) set on an aluminum wheel(5). Twenty SRM bullets were manufactured at thesame time. After cutting one signature, the cylinders (3)were rotated 60° to cut the next signature until all sixsignatures were completed. There was a 5° tilt for the“V” block (4) alignment on the aluminum wheel (5), sothat a 5° twist in the bullet signature land could bemade on the SRM bullets. That gave the SRM bullet ashape close to that of the master. Detailed informationfor the manufacturing process and quality control canbe found in Ref. [12]. Figure 2 shows a SRM 2460standard bullet (right) with a master bullet from theATF National Laboratory Center (left), and a prototypestandard bullet (center). The duplicated bullet signa-tures on the surface of the standard bullets are highlytwo-dimensional, and hence are very smooth along themachining direction perpendicular to the bullet signa-ture. Therefore, these bullets may be characterized bytheir topographic profile signatures, machined on theland engraved areas and measured, for example, with astylus instrument.

3. A Bullet Profile SignatureMeasurement System

Measurement results showed that the bullet profilesignatures on the standard bullets can be manufacturedwith high uniformity [10,11]. However, there were

small differences when comparing profile signatures ofthe SRM bullets with the virtual bullet signature stan-dard, and when comparing the signatures between dif-ferent SRM bullets. It is therefore important to define atraceable parameter and to develop a measurement sys-tem for measuring profile signature differences. Thisparameter is particularly important for the production,inspection and quality control of the SRM bullets.

It was decided to adapt the signal processing func-tions of auto-correlation and cross-correlation for thebullet signature comparisons [13,14]. Because the bul-let signatures can be considered as random profiles,their auto-correlation functions (ACF) decay withincrease in the absolute value of the shift distance. Thisstatistical property is very useful for the bullet profilesignature comparisons for quantifying the difference ofbullet signatures. When two bullet profile signaturesare compared with each other, one is taken as the refer-ence signature A and the other is the compared signa-ture B:

• If the two profile signatures are exactly the same,A = B, their ACF achieves the maximum value (1.00)when the shift distance is zero.

• If two compared profile signatures A and B haveessentially the same pattern but small differences inthe profile details, then A =∼ B. For example, whentwo bullets are fired from the same gun, their profilesignatures may have strong correlation. With the shiftdistance changing, their CCF will have a maximumvalue but not as large as 1.00, because there are some

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Fig. 2. A master bullet from ATF National Laboratory Center (left), a prototype standard bullet(center), and a SRM 2460 standard bullet (right).

differences between these two correlated profile sig-natures.

• If signatures A and B come from bullets fired fromdifferent guns, there should be only small correlationbetween the two bullet signatures, B ≠ A. With theshift distance changing, only random variationsappear on the CCF curve without a clear correlationpeak.

From the cross-correlation function (CCF) we calculatea parameter called CCFmax, which is the maximumvalue of the CCF when the two compared profiles arein phase. Although the CCFmax can be used for the pro-file signature comparison, it is not a unique parameter.Based on the definition of the cross-correlation func-tion [13], if two compared signatures have the sameshape but different vertical scales, their CCFmax is still100 % even if they are two different signatures.Therefore, a parameter, signature difference Ds, is pro-posed for quantifying the profile signature differences[13]. It is calculated as follows:

• At the shift where the CCFmax between signature Band A occurs, construct a new profile ZB – A (X),which is equal to the difference of the compared pro-file signature ZB (X) and the reference profile signa-ture ZA (X):

ZB – A (X) = ZB (X) – ZA (X). (1)

• Calculate the Rq (root-mean-square roughness, seeRef. [15]) value for the new profile ZB – A (X). We callthis parameter Rq(B – A).

• Calculate the signature difference Ds between signa-tures B and A defined as

Ds = Rq2(B – A) /Rq2(A) (2)

where Rq2(A) is the mean square roughness of the ref-erence signature ZA (X), used here as a comparison ref-erence. From Eqs. (1) and (2), it can be seen that whentwo compared profile signatures are exactly the same,ZB – A (X) = 0, then Rq2(B – A) = 0, and Ds = 0.

A bullet profile signature measurement program wasdeveloped to calculate the above parameters. A screenoutput of the measurement program is shown in Fig. 3.These modified profiles result after curvature removal,resampling, and bandpass filtering (2.5 µm to 250 µm)of the measured profiles [12,14]. The top profile is thevirtual profile signature standard, or “Signature A”,which is one of the six modified profiles from the bul-let signatures of the six master bullets provided by theATF and the FBI. The second profile shows the meas-

ured bullet signature, or “Signature B”, which in thiscase is a profile signature from the No. 1 land impres-sion of the S/N SRM 2460-001 bullet. Both profileshave a data spacing of 0.25 µm. The cross correlationpeak CCFmax is equal to 99.55 %. At this position, anew profile, Signature (B – A) (see the bottom profilein Fig. 3), is constructed, which is equal to the differ-ence between the two compared signature profiles.Then the signature difference Ds is calculated from Eq.(2) to be 0.92 %.

The six signatures on each of the 40 SRM bulletshave been measured. The measurement results showthat all CCFmax values for the 240 measured profile sig-natures, when compared with the virtual profile signa-ture standard, are higher than 95 %, and most are high-er than 99 % (Fig. 4). Considering that the measuredprofile signature is exactly the same as the virtual stan-dard when CCFmax = 100 % and Ds = 0, the measure-ment results have demonstrated high reproducibility forboth the NIST bullet signature measurement systemand the SRM bullets. Measurement results also showedthat the machined profiles are highly two-dimensionaland therefore are very smooth along the machine direc-tion. In other words, they are highly uniform and yieldthe same profile along the land impression of the SRMbullets. Based on NIST Technical Note 1297 [16], anuncertainty analysis procedure is currently in progressto report the measurement results for both CCFmax andDs with a 95 % confidence level.

Compared with existing commercial algorithms forbullet and casing image signature comparisons, Theproposed CCFmax and Ds parameters have several fea-tures [13,14]:

• They are easy to understand and use, and are trace-able to the length standard and the virtual bullet sig-nature standard.

• The same basic parameter and algorithm can be usedfor quantifying signature differences for both 2D-profile bullet signatures and 3D-topography signa-tures. A prototype 3D-topography characterizing sys-tem for standard cartridge casings has been devel-oped recently.

• From Eqs. (1) and (2), it can be seen that for the col-lection of all 2D-profile and 3D-topography compar-isons, the minimum signature difference is Ds = 0,which occurs when, and only when, these two pro-files or topographies are exactly the same. Thatmeans, when any two compared 2D-profiles or 3D-topographies have a signature difference of Ds = 0,these two profiles or topographies must be exactlythe same (point by point).

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• The measurement results of 240 bullet signatures on40 SRM 2460 standard bullets showed that there is astrong linear correlation between CCFmax and Ds [14].Therefore, in practice, either parameter can be usedfor representing bullet signature differences of theSRM bullets.

• The characteristic parameters for bullet and casingsignature comparisons, CCFmax and Ds, are directlyderived from a statistical process, and have a poten-tial for ballistics comparisons of bullet and casingsignatures. One drawback of this approach is thatscale changes and nonlinearities of the instrument inthe X- and Y-directions could detract from the obser-vation of high correlation between similar profiles ortopography images. However, for a well-calibratedbullet and casing signature measurement system, thiseffect should be very small.

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Fig. 3. Bullet signature comparison between the signature of the No. 1 land of S/N 001 SRM 2460 (Signature B, the second profile from the top)and the virtual standard (Signature A, the top profile). The maximum of the cross correlation function CCFmax = 99.55 %, the signature differenceDs = 0.92 %. The profile difference of two signatures, B – A, is shown as the bottom profile with different scale.

Fig. 4. CCF distribution for 240 bullet signatures of 40 SRM bullets.All CCF values are higher than 95 %, most are even higher than99 %. CCF = 100 % means the measured bullet signature is exactlythe same as the virtual bullet signature standard (point by point).

4. Traceability for Nationwide BulletSignature Measurements

The profile signature measurements for SRM bulletsmust be traceable to the SI unit of length. This isensured by using a set of calibration and check stan-dards, and standardized measurement and uncertaintyprocedures in the NIST Surface Calibration Laboratory[17].

In order to establish measurement traceability ofimage signature measurements at local laboratories toNIST, ATF and FBI, we propose to use SRM 2460 stan-dard bullets following a flow diagram shown in Fig. 5starting with the six master bullets that ATF and FBIprovided. The six master bullets were profiled at theNIST Surface Calibration Laboratory using a stylusinstrument, as shown in Fig. 5, branch 1. The set of sixdigitized 2D profile signatures was used as a 2D virtu-al standard for profile signatures to control a numerical-ly controlled diamond turning machine at NIST to pro-duce the SRM bullets as physical standards. One ofthem, numbered SRM 2460-001, would be kept atNIST as a check standard. This check standard wouldbe routinely measured at the NIST Surface CalibrationLaboratory, and compared with the virtual standard formeasurement quality control, as shown in Fig. 5,branch 2. Other SRM bullets would be distributed to

three ATF Laboratory Centers, to the FBI Central labo-ratory, and to FTI (Forensic Technology Inc., Montreal,Canada, IBIS manufacturer), leaving the remainingSRM bullets for purchase through the NIST StandardReference Material (SRM) Office with the intent thatthese bullets would be utilized by firearm examiners ontheir respective IBIS. At the ATF National LaboratoryCenter, the SRM bullets would be measured under a setof pre-determined standardized IBIS testing conditions.The resulting digitized optical intensity images wouldbe used as the image signature standard and be trans-ferred to local IBIS sites. In principle, a virtual standardfor the 3D image signatures might also be generated bycomputer-imaging techniques using the 2D virtual pro-file signature standard as input, and might be verifiedby measured IBIS images on SRM bullets. By measur-ing these SRM bullets at local IBIS sites, and compar-ing the measured images with those of the image signa-ture standard measured at ATF under standardized con-ditions, differences in IBIS calibrations and testingconditions between the local IBIS sites and ATF can bedetected. That could enable traceability for ballisticsmeasurements nationwide to NIST, ATF, and FBI, andensure the measurement quality control of local IBISsites [18].

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Fig. 5. A proposed national bullet signature measurement traceability and standardization sys-tem. The arrows indicate different types of functions such as measurement, calculation and sim-ulation.

5. SRM 2461 Standard Casings

Electroforming is a commercial technique that hasbeen successfully used for replication of surface rough-ness specimens [8]. The same technique is being uti-lized for the manufacture of SRM 2461 standard cas-ings. In April 1998, five master casings were producedby a standardized firing procedure at the ATF NationalLaboratory Center. By replication of two master cas-ings, 21 prototype standard casings were manufacturedby two manufacturers [19]. The IBIS was used for theinitial tests of these prototype standard casings. Forcasing signature comparisons, the IBIS correlationscore may be calculated between a pair of images ofeither the firing pin impression, the ejector mark or thebreech face impression.

From the image comparisons between different pro-totype standard casings, it can be seen that these images

show high reproducibility. For example, Fig. 6 showsfiring pin and breech face signature comparisonsbetween No. P11 and No. P21 prototype standard cas-ings. Figure 7 compares ejector mark impressionsbetween the No. P21 and No. P31 casings. Both figuresshow close agreement between the two compared cas-ing images. The topography signature comparisonsbetween the firing pin of No. P21 and P31 casings havealso been conducted using the recently developed cas-ing topography signature comparison system, which isa 3D version of the bullet profile signature comparisonsystem, as mentioned before. The preliminary compar-ison result shows CCFmax = 99.09 %. These compar-isons indicate good surface reproducibility betweendifferent prototype standard casings. Based on theseinitial test results, the basic design for the SRM 2461standard casings has been made, and the SRM casingsare planned for fabrication in the near future.

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Fig. 7. Ejector image comparison between P21 (left) and P31 (right) prototype standard cas-ings.

Fig. 6. Firing pin and breech face image comparison between P11 (left) and P21 (right) proto-type standard casings.

6. Summary

A new standard for ballistics measurements—SRM2460/2461 standard bullets and casings—is beingdeveloped at NIST. The SRM 2460 standard bullet isdesigned as both a virtual and a physical standard. Thevirtual standard is a set of six digitized bullet profilesignatures acquired from six master bullets provided byATF and FBI. From these profile signatures, 40 physi-cal standards, the SRM bullets were produced in theNIST Instrument Shop.

A new parameter, signature difference Ds, was devel-oped for both the 2D bullet profile signature and 3Dcasing topography signature comparisons using auto-and cross-correlation functions. A bullet signaturemeasurement system has been established at NIST forthe measurements of the standard bullets and standardcasings. Measurement results for 40 SRM bullets witha total of 240 signatures show very high reproducibili-ty. A traceability system is proposed to establish nation-wide ballistics measurement traceability to NIST, ATF,and FBI. Prototype standard casings have also beendeveloped at NIST using an electro-forming technique.SRM 2461 standard casings are planned for fabrication.

The SRM bullets and casings aim to support theNational Integrated Ballistics Information Network(NIBIN) in the United States. They can be used forchecking instrument calibration, for maintaining quali-ty control in ballistics measurements, and for promot-ing a nationwide ballistics measurement traceabilitysystem, and therefore, have great potential to supportnationwide crime fighting and to strengthen homelandsecurity.

Acknowledgments

The funding for this research was provided by theNational Institute of Justice (NIJ) through the Office ofLaw Enforcement Standards (OLES) at NIST. Theauthors are grateful to R. Thompson and J. Miller of theBureau of Alcohol, Tobacco and Firearms (ATF) fortheir contributions in this project; to M. McLean of theForensic Technology Inc. for the micrographs of Figs.6 and 7. The authors are also grateful to T. Vorburger,B. Dutterer, C. Johnson, B. Renegar and A. Zheng ofNIST for their contributions in manufacturing andmeasurement of the SRM bullets.

7. References

[1] P. Weiss, A Shot in the Light—Precise Bullet Replicas Take Aimat Crime-fighting Standard, Sci. News 163, 23-25 (2003).www.sciencenews.org/20030111/bob9.asp.

[2] Office of Firearms, Explosives and Arson, ATF: ATF’s NIBINProgram, 1998 AFTE (Association of Firearm and Tool MarkExaminers) Workshop, July 12-17, Tampa, FL (1998).

[3] W. Casey, (Deputy Superintendent, BPD), J. Wooten (AssistantDirector, ATF) and R. Murch (Deputy Assistant Director, FBI),National Integrated Ballistics Identification Network, 1998AFTE Workshop, July 12-17, Tampa, FL (1998).

[4] VIM (International Vocabulary of Basic and General Terms inMetrology), by BIPM, IEC, IFCC, ISO, IUPAC, IUPAP, andOIML, Geneva (1993).

[5] J. Song, T. Vorburger, and M. Ols, Establishment of aVirtual/Physical Standard for Bullet Signature Measurements,Proc. 2001 NCSL, Washington, DC, August 2001.

[6] E. Teague, F. Scire, and T. Vorburger, Sinusoidal ProfilePrecision Roughness Specimens, Wear 83, 61 (1982).

[7] T. Vorburger, J. Song, C. Giauque, T. Renegar, E. Whitenton,and M. Croarkin, Stylus-laser Surface Calibration System,Precision Eng. 19,157-163 (1996).

[8] J. Song, T. Vorburger, and P. Rubert, Comparison betweenPrecision Roughness Master Specimens and Their Electro-formed Replicas, Precision Eng. 14, 84-90 (1992).

[9] J. Song, C. Evans, M. McGlauflin, E. Whitenton, T. Vorburger,and Y. Yuan, NIST Virtual/Physical Random Profile RoughnessCalibration Standards, Proc. SPIE 3426, 213 (1998).

[10] J. Song, T. Vorburger, R. Clary, M. McGlauflin, E. Whitenton,and C. Evans, NIST Random Profile Roughness Specimens andStandard Bullets, Proc. 2000 Measurement Science Conference(MSC), California, January 2000.

[11] J. Song and T. Vorburger, Development of NIST StandardBullets and Casings Status Report, NIJ Report 603-00, NationalInstitute of Justice, U.S. Department of Justice, November2000.

[12] E. Whitenton, C. Johnson, D. Kelley, R. Clary, B. Dutterer, L.Ma, J. Song, and T. Vorburger, Manufacturing and QualityControl of the NIST Standard Reference Material 2460Standard Bullet, Proc. 2003 ASPE (American Society forPrecision Engineering), Oct 28-31, 2003, Portland, Oregon, pp.99-102.

[13] J. Song and T. Vorburger, Proposed Bullet SignatureComparisons Using Autocorrelation Functions, Proc. 2000NCSL, Toronto, July 2000.

[14] L. Ma, J. Song, E. Whitenton, A. Zheng, T. Vorburger, and J.Zhou, NIST Bullet Signature Measurement System for SRM(Standard Reference Material) 2460 Standard Bullets, J.Forensic Sci. 49 (4), 649-659 (2004).

[15] ASME B46.1-2002, Surface Texture, American Society ofMechanical Engineers, New York (2002).

[16] B. Taylor and C. Kuyatt, Guidelines for Evaluation andExpressing the Uncertainty of NIST Measurement Results,NIST Technical Note 1297, National Institute of Standards andTechnology, Gaithersburg, MD (1994).

[17] J. Song, T. Vorburger, and M. Ols, Establishment ofMeasurement Traceability for NIST Standard Bullets andCasings, Proc. 2001 Measurement Science Conference (MSC),Anaheim, CA, January 2001.

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[18] J. Song, T. Vorburger, R. Clary, E. Whitenton, and M. Ols,Establishment of Ballistics Measurement Traceability usingNIST SRM 2460 Standard Bullets, Proc. 2002 NCSL, SanDiego, CA, August 2002.

[19] J. Song, T. Vorburger, and M. Ols, Progress in Developing NISTStandard Casings, Proc. 2002 Measurement ScienceConference (MSC), California, January 2002.

About the authors: Jun-Feng Song is a mechanicalengineer in the Precision Engineering Division andEric Whitenton is a mechanical engineer in theManufacturing Metrology Division, both divisions arein the NIST Manufacturing Engineering Laboratory.David Kelley is an electrochemist in the MetallurgyDivision of the NIST Materials Science andEngineering Laboratory. Robert Clary is a machinist inthe Fabrication Technology Division of the NISTManufacturing Engineering Laboratory. Li Ma is aguest researcher from the Catholic University ofAmerica. Susan Ballou is a program manager in theOffice of Law and Enforcement Standards at NIST.M. Ols is a firearm and toolmark examiner at theBureau of Alcohol, Tobacco and Firearms (ATF). TheNational Institute of Standards and Technology is anagency of the Technology Administration, U.S.Department of Commerce.

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