AFTE Store - The Utility of Double-Casting for Creating Cartridge Case Reproductions

Due to the variability that arises in the breech face and firing pin impressions on multiple cartridge cases fired by the same
firearm, a method of reproduction is needed to create standardized cartridge cases. A process called double-casting has
been used that involves creating a silicone rubber mold of a cartridge case, and then uses a plastic resin casting material
to make a cartridge case reproduction. The first part of this study analyzed casts of the National Institute of Standards
and Technology (NIST) standard cartridge case (SRM 2461). Integrated Ballistic Identification System® (IBIS) data and
visual comparisons showed the method of double-casting was able to reproduce fine detail that is visible even at 100× magnification. Prior to widespread use, it is important to characterize the effects of within- and between-mold variability of the casts. Cartridge cases fired by three firearms were replicated using the double-casting process and entered into an IBIS®. Some instances of significant differences between the mold and cast sets were found. However, visual comparisons of 1) the casts to their original cartridge cases, and 2) the casts to other casts of the same cartridge case both showed that the double-casting method reliably reproduces the fine detail that is present on the original cartridge cases.