NIST RM (Reference Material) 8240/8250 Standard Bullets and Casings Project
Jun-Feng Song, Theodore V. Vorburger, Susan M. Ballou, M Ols
The NIST RM (Reference Material) 8240/8250 Standard Bullets and Casings Project aims to support the National Integrated Ballistics Information Network (NIBIN) in the U.S. Two prototype standard bullets were developed in 1998 with all six lands manufactured with the same bullet signature (see Fig. 1, middle). For the development of RM 8240 standard bullets (see Fig. 1, right), original signatures were profiled on six master bullets from central laboratories of the Bureau of Alcohol, Tobacco and Firearms (ATF) and the Federal Bureau of Investigation (FBI). One of the master bullets is shown in Fig. 1, left. These master bullets were profiled at NIST's Surface Calibration Laboratory using a stylus instrument. The six digitized bullet signatures were stored in a NIST computer as the 2D virtual bullet signature standard for the manufacturing of standard bullets. In January 2002, twenty RM 8240 standard bullets were manufactured at NIST's Instrument Shop using a numerically controlled diamond turning machine. Test results showed high repeatability and reproducibility of the bullet signatures. High repeatability here means that the bullet signatures are essentially identical over different axial sections on the same standard bullet. High reproducibility means that the bullet signatures on different standard bullets are essentially identical.A new parameter using autocorrelation functions has been developed at NIST for bullet signature comparisons. It can be used for quantifying signature differences for both 2D bullet signatures and 3D casing signatures. When identical 2D or 3D signatures are compared with each other, their signature difference, calculated by the NIST algorithm, is zero. Conversely, when any 2D or 3D signature difference is calculated as zero, these two compared signatures must be exactly the same (point by point). Because signature information of all 2D or 3D data points is used for comparison, the new parameter could have high sensitivity, and can ensure high repeatability and reproducibility. Based on this parameter and algorithm, a measurement system for 2D bullet signatures was developed at NIST for the tests of RM 8240 standard bullets.A traceability diagram was also proposed by NIST for local ballistics measurements traceable to the National Laboratory Center of the ATF and to the FBI. By measuring the RM bullets using the Integrated Ballistics Identification System (IBIS) at ATF under standardized measurement conditions, a set of 3D digitized images for these RM bullets can be established as the 3D virtual bullet signature standard, and transferred to local IBIS sites. Meanwhile, the NIST RM bullets are available for purchase at local IBIS sites. By measuring the RM bullets at the local IBIS sites, and comparing the measured images with those of 3D virtual bullet signature standards measured at ATF under the standardized IBIS measurement conditions, ballistics measurements at local IBIS sites can be quality controlled, and traceable to the national laboratory center.Prototype standard casings with three different designs were developed in 2000 using an electro-forming process. Test results showed high reproducibility for the casing signatures. RM 8250 standard casings are planned for fabrication.The NIST RM 8240 standard bullets and RM 8250 standard casings can be used for the establishment of traceability for local ballistics measurements to the national laboratory center. These new standards could ensure ballistics measurement quality control and measurement unification nationwide, and promote ballistics laboratory accreditation.
9th European Network of Forensic Science Institutes, (ENFSI) Expert Working Group Firearms
, Vorburger, T.
, Ballou, S.
and Ols, M.
NIST RM (Reference Material) 8240/8250 Standard Bullets and Casings Project, 9th European Network of Forensic Science Institutes, (ENFSI) Expert Working Group Firearms, Bratislava, SL
(Accessed February 24, 2024)