1. A method of providing ammunition cartridges for use in a rifle to enable the identification and selection of the most accurate propellant load weight for the rifle, comprising the steps of: providing a first kit comprising multiple cartridges, wherein at least some of the multiple cartridges are differentiated by propellant load weight, and wherein the value of differentiation of propellant load weight between cartridges is a number of grains selected from the range of 0.1 grains to 0.5 grains; and wherein each cartridge has a different target propellant load weight, and is manufactured by means of an automated granule portioning system comprising: a volumetric assembly comprising a top plate, a bottom plate, and a telescopic chamber engaged with the top plate and the bottom plate, the telescopic chamber comprising a plurality of chamber tubes, wherein the volume of the telescopic chamber is adjustably based upon the position of the top plate relative to the bottom plate, and the position of the top plate relative to the bottom plate is adjustable by a gear mechanism, the volumetric assembly being arranged to receive a portion of propellant granules into the telescopic chamber to fill the volume of the telescopic chamber; a weighing device, the weighing device being capable of weighing the portion of propellant granules received in the telescopic chamber, and comparing the weight of the portion of granules to a target propellant load weight corresponding with the cartridge; and a motor, wherein the motor is capable of rotating the gear mechanism to adjust the volume of the telescopic chamber after the weighing device determines that the granule weight of the portion of granules is different than the target propellant load weight corresponding with the cartridge.