Automated computer matching systems do not provide conclusive results. Rather, a list of potential candidates are presented that must be manually reviewed. When applying this technology to the concept of mass sampling of manufactured firearms, a huge inventory of potential candidates will be generated for manual review. This study indicates that this number of candidate cases will be so large as to be impractical and will likely create complications so great that they cannot be effectively addressed.
http://www.nraila.org/media/PDFs/CADOJ_report.pdf