These cartridges used a Cal. 30 Service Case (30-06) with spitser type bullet for use in the SALVO field trials. Some loadings have the rear bullet with longitudinal grooves to allow for the propellant gasses to ignite a 2 grain charge between the 2 bullets to obtain separation in the bore for dispersion tests. The first specimen has a red coloured tip for marking purposes but there are also a number of specimens with different coloured tips as can be seen below but the reason is not known. It is assumed that these were for internal use to identify different test samples or loadings.