A comparison microscope employing the standard optical comparison method and confocal microscopy with subsequent cross correlation topography analysis were used to correctly identify cases fired from a set of ten (10) consecutively made pistol slides. The mathematical identifications were based on the breech face impression without the firing pin aperture shear marks. Fifteen (15) unknown cartridge cases were compared to test fired cartridge case sets from the consecutively manufactured slides. In addition, five (5) “persistence cases” were also compared to the slides. Cartridge cases that comprised test fires from ten (10) consecutively manufactured Ruger slides, fifteen (15) unknown cases, and five (5) “persistence study” cases were received from Thomas Fadul from the Miami Dade Crime Laboratory. The cases were microscopically examined and the results were later confirmed as accurately associating all of the questioned cases back to the correct pistol slide sources. These results were not communicated to the project team until after the surface metrology and correlations were completed. A Nipkow disc confocal microscope was used to gather the 3D topography data from the breech face area of each case. The data were then trimmed to remove any uninformative areas. Preprocessing software then was employed to identify outlier and dropout points, which are typical artifacts in this type of surface measurement. These outliers and dropouts were then interpolated and masked from further correlations. Next, the software applied a Gaussian filter to the data to remove long wavelength waviness and short wavelength noise. After the filter, the data were then leveled and were registered in the X, Y and θ directions to locate the maximum correlation position. After the registration was completed, the software applied the cross correlation algorithm to quantify the similarity between two cases.