Thanks Semi

I am a rookie at ml but my profession is Quality Engineering. There is natural varience in the way Charlie and anyone esle measures powder. That is why Charlie's 50 grains of powder ranged from 49.8 to 50.3 grains of powder. Manufactures take this in consideration when they make a product, in this case a powder measure, and set what the acceptable min/max is for their product. In Charlie's case his tolerance would be 50 grains +.3 grains -.2 grains of powder to get his desired shooting results.
Now as Semi has said you add the different powder weights and you throw in another set of variables. Bottom line use the same powder measure every time, and when someone tells you they are using 100 grains of powder keep in mind you might have to add or subtract to get it to peforme the way you want it to.