What were you trying to detect by weighing the individual rounds?
Hopefully not light/heavy powder charges, as 1 gram = 15.43 grains, or more than 1.5x the heaviest charge weight I saw on quickly glancing into the never-used .45 section of the little Lyman pistol caliber data book sitting on my desk. Further, the brass cases and bullets weigh far more than the powder, so even small variations in the weights of those components, percentage-wise, would quickly obscure any variance in powder charge.