Standard Reference Material (SRM) 2461, 

Standard Cartridge Case

T.V. Vorburger (tvtv@nist.gov), W. Chu, A. Zheng,

T. B. Renegar, J. Yen, J.F. Song, J. Villanova, L. Ma,

R.M. Thompson

National Institute of Standards and Technology (NIST)

Gaithersburg, MD 

Martin Ols

Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF)

Ammendale, MD

Forensics at NIST Conference

Gaithersburg, MD

November 28, 2012
Contents

• Introduction to SRM Bullets and 

Cartridge Cases

• Topography Measurement of SRM 

Cartridge Cases

• Traceability

• User Acquisition Procedure

• Availability
Funding Provided by

• National Institute of Justice

NIST Law Enforcement Standards Office

NIST Standard Reference Materials Program

Note:

Certain commercial equipment may be identified in this 

presentation in order to specify an experimental 

procedure. This does not imply recommendation or 

endorsement by NIST, nor does it imply that the 

equipment are the best available for the purpose. 
SRM 2460 Standard Bullet and

SRM 2461 Standard Cartridge Case

• For demonstrating consistency in image acquisitions 

of bullets and cartridge cases from place to place 

and one time to another

• Requires high degree of similarity from one unit to 

another 

• Must have characteristics of real bullets and 

cartridge cases
SRM 2461 Standard Cartridge Case Recently 

Made Available 

• Cartridge cases fabricated using a metal electroforming process:

- Negatives are made from a master cartridge case

- Positive replicas are then made from the negatives
Firing Pin

Breech Face

Ejector mark

Topography Images for the 

Standard Cartridge Case 

These images should be the same for all 

units.
Contents

• Introduction to SRM Bullets and Cartridge 

Cases

• Topography Measurement of SRM 

Cartridge Cases

• Traceability

• User Acquisition Procedure

• Availability
SRM 2461 Standard Cartridge Case

Confocal microscope used to image 3D cartridge case topography
SRM 2461 Analysis – Breech Face

Processing steps:

-Trimming 

-Removal of outlier data

-Form & noise filtering

-Image registration

-Correlation calculation 
SRM 2461 Analysis – Breech Face

Correlation scores of 2461-155 (Breech Face Master) versus 

population set
SRM 2461 Analysis – Firing Pin

Processing steps:

• Removal of outlier data

• Form & noise filtering

• Image registration

• Correlation

Correlation program showing an example Firing 

Pin correlation

Correlation scores of 2461-153 (Firing Pin 

Master) versus population set
SRM 2461 Analysis – Ejector Mark

Processing steps:

• Trimming

• Removal of outlier data

• Form & noise filtering

• Image registration

• Correlation

Correlation program showing an example 

Ejector Mark correlation

Correlation scores of 2461-260 (Ejector Mark 

Master) versus population set
NIST Statisticians participated in the analysis of the 

uncertainty estimates and control values, and 

preparation of the Certificate.

Both SRMs and their Certificates include User 

Guides as appendices
Data on the SRM 2461 Certificate

 Table 1. Areal Cross Correlation Maximum ACCFmax

and Signature Difference Dsfor the SRM 2461 

Standard Cartridge Cases 

(95 % Confidence 

Interval) ACCFmax Ds

Breech Face > 94.3 % < 11.2 %

Firing Pin > 98.0 % < 4.0 %

Ejector Mark > 93.7 % < 12.2%
Contents

• Introduction to SRM Bullets and Cartridge Cases

• Topography Measurement of SRM Cartridge Cases

• Traceability

• User Acquisition Procedure

Emphasis on the ATF’s National Integrated 

Ballistics Information Network (NIBIN) and 

the system it uses, the Integrated Ballistics 

Identification System (IBIS)

• Availability
Two Traceability Chains

NIST 

SRMs

NIST Master Standards,

SRM 2460-001 

SRM 2461-153,155,260,...

Golden Images 

Maintained for NIBIN 

by ATF Nat’l Lab Ctr. 

Bullet & Casing Masters

On-Line Bullet/Casing 

Topography Images

SRM 2460 Bullet Master 

SRM 2461 Casing Masters

NIBIN Crime Laboratories

SRM 2460-xxx, SRM 2461-yyy

NIST Bullet/Casing 

Topography 

Measurement System 

SI unit of 

Length (Meter)

Other Topography 

Measurement Systems

SRM 2460-zzz

SRM 2461-uuu

IBIS Acquisition at ATF 

Nat’l Lab Ctr. 
SRM 2461 Documentation Includes a User 

Guide mainly for NIBIN Users
Use “TRAX GOLDEN CC IMAGE”

for control chart scores

Example of Correlation Results for IBIS 

Acquisitions of SRM 2461 
Table 2. A Control Chart for Breech Face (BF) Scores of SRM 

Cartridge Case (Sheet 3 "BF")

Date BF Score

Dynamic 

CL Fixed CL File Name Notes

3/23/2010 376 214 SRM2461-018-23MAR10A

4/23/2010 403 358 214 to be added

5/23/2010 368 352 214

6/23/2010 422 351 214

7/23/2010 357 341 214

8/23/2010 398 347 214

9/23/2010 447 344 214

10/23/2010 382 345 214

11/23/2010 363 342 214

12/23/2010 427 344 214

1/23/2011 414 348 214

2/23/2011 379 348 214

214

214

An Excel Sheet with Control Chart for Tests of 

SRM Cartridge Cases 
Proposed Control Limits for NIBIN Acquisitions of 

SRM 2461, Based on Results of the National Ballistics 

Imaging Comparison

20

Mean Std. 

Dev.

95 % 

Control 

Limit

Breech 

Face 276 38 214

Firing 

Pin 233 38 171

Ejector 

Mark 968 345 400
Availability of SRM 2461

• Cost: $302

• Available since July 2012

• 27 units distributed

• 110 units available

• The certification of SRM 2461 is valid until 

30 September 2021, with proper handling.