Inter-Composition Bullet Comparisons
For Max Phase, copper jacket to lead comparisons, IBIS correlated 80% of reference samples to their known match outside of the top 20 positions.
IBIS scores were slightly improved for Max Phase, lead to copper jacket comparisons, with 60% of reference samples correlating to their known match within the top 20 positions (Fig. 5).
Thus for IBIS inter-composition comparisons, numerous samples were located outside the correlation area of search and would likely result in many missed hits.
IBIS was also less able to distinguish between inter-composition bullets fired from the different Para-Ordnance barrels as 100% of comparisons found a bullet fired from a different barrel higher in the correlation list.
IBIS image quality for lead bullets was poor, and as such there was little value in comparing those images with more detailed copper-jacketed images.
An operator would likely not be able to identify a possible match between the lead and copper-jacketed bullet pairs (Fig. 6).
BulletTRAX-3D was more successful than IBIS at identifying matches within the inter-composition comparisons.
In copper jacket to lead comparisons, 100% of reference samples were correlated to their known matches within the top 20 positions (90% of matches were within the top 10).
For lead to copper jacket comparisons, BulletTRAX-3D correlated 90% of reference samples to their known match within the top 10 and the remaining 10% outside of the top 20 (Fig. 5).
For inter-composition comparisons, BulletTRAX-3D was successful at distinguishing between the
different Para-Ordnance barrels as 90% of comparisons found the bullet fired from the reference barrel in the first position in the correlation list.
Image quality was also better using BulletTRAX-3D.
Although visual identification of the inter-composition bullet pairs is more difficult than with bullets of the same composition, it is possible for an operator to find enough details in common to identify a potential hit (Fig. 7).