2007
Julianna Price
San Francisco, CA
Objective: (1) Introduce the Thunder Five revolver. (2) Brief history of the company, Munitions International Laboratories Incorporated (MILI). (3) Give a detailed description of the manufacturing process of the Thunder Five, which consists mostly of investment casting. (4) Briefly discuss the effects investment cast rifling could have on the identification of fired bullets. Methodology: The manufacturing facility of the Thunder Five was toured to observe how the rifling is investment cast into the barrel. While at the factory, two revolvers were test fired and 45 test fires were obtained from each firearm. Several specimens of barrels and frames from different stages of the manufacturing process were also obtained. Results: Only a preliminary examination of the test fires has been conducted so far and further study would have to be performed to conclude whether or not investment cast rifling produces unique markings inside each barrel. Conclusions: In general test fires from the Thunder Five have poor rifling and several have deformities. The concern for the firearms examiner is the fact that the rifling in the Thunder Five is produced by investment casting. Without any further research there is no way to know whether or not rifling that is investment cast has individual characteristics that will allow a firearm to be uniquely associated with a bullet fired through the barrel. It is possible that because each barrel is made by the same mold that similar microscopic features will be imparted on bullets fired through different barrels. But it is also possible that because of the way in which the ceramic mold is formed that the individual silicate grains could form a unique surface pattern on each mold which would then be imparted onto the steel poured in to make the final product. The finishing processes applied to the steel frame might also create a more unique surface inside the barrel.