Influence Factors Regarding the Effectiveness of Automated Ballistic Comparison on 0.38 Special Caliber Bullets and Cartridge Cases

Abstract

Factors influencing effectiveness of automated comparisons, test-fired bullets, and cartridge cases from 0.38 Special revolvers were logged into the Evofinder Ballistic ID System. Tests were performed as follows: First test correlated test-fires of the same type, second test compared different types of ammunition components, third test replicated the second test in a larger database, and fourth test replicated the third test with students having no previous firearm identification experience. System effectiveness with projectiles in the first test was 0.89. With cartridge cases, effectiveness was 0.79 with combined results, but analysis of separate results by breech face and firing pin revealed low effectiveness by breech face (0.40). In the second, third, and fourth tests, effectiveness with projectiles were 0.61, 0.51, and 0.44. In addition, these tests had effectiveness with cartridge cases equivalent to 0.55, 0.43, and 0.44. Results are useful to establish routine protocols, system improvements, or comparative assessment of other electronic systems.

Reproducibility and persistence of individual marks on 3000 fired bullets from five Chinese Norinco QSZ‐92 9 × 19 mm pistols, and the search performance of Evofinder® to a 1000 firearm database of the same model firearm

“…The development of image analysis algorithms for comparing the similarity of tool marks has progressed rapidly in the past decade; this implies that fully automatic firearm identification may be realized in the near future. Furthermore, firearm identification should be converted to an objective method and subjective factors should be reduced for further improvements [18][19][20][21][22]. Dos Santos selected sixteen 0.38 SPL calibre revolvers, and the test-fired bullets were logged into a ballistic identification system, Evofinder ® (ScannBI Technology).…”

“…The number of matches on each position, divided by the total number of results on each configuration, provides the cumulative probability to find a match until position n , which was defined as the effectiveness of the system. The system's effectiveness with bullets is 0.89, indicating the good quality of fired bullet marks and the system's matching capability [19].…”