Over the course of that last year, I have developed a system in which the weight variance question has had little or no effect on final product. I never make a batch less than 120 mls and more often that not the batch size is greater that 500 mls. Errors of 1 gram in a 500 ml batch doesn't effect the end product enough to cause a problem with taste or nic value. Since any calculated error is across the entire spectrum of ingredients, the precentage values are equalized. I appreciate that there are some that are very interested in being exact.