As long as you are dropping powder uniformly from one session to the next, then you might want to check density.
According to usually reliable sources, powder manufacturers set the standard for density of powder a long time ago, settling on an allowed variance of 16% This means that the powder can be 16% less dense or 16% more dense than the can you bought that was right on, or the can you started with was 16% light and the next was 16% heavy. This is why it is important to measure the density of every can or bottle of powder you use, and label it, if you are loading for accuracy. This does not mean that powders WILL vary that much, it is only the maximum allowed, by mutual consent of the powder makers. Winchester at one time claimed a max variance of +/- 2.5% Powder manufacturers catering to match shooters will have tighter tolerances, as well. Also remember that temperature and humidity will affect density, so the old "load in winter shoot it in winter....etc." saw has validity.
Lee has a formula posted in their technical help section that deals with density and the use of their dippers or bushings, in the case of shotgun loading. You do not really need to know the exact density of the powder, since your really interested in keeping things consistent from loading to loading, so you need to be able to compare the new can of powder to the old one that worked so well for you in the past. BTW, the Lee dippers are labeld in cubic centimeters.
You can determine the density of the powder as compared to the standard, which is water at room temperature. The number assigned to water density is "1" All you need do is divide the weight of the powder by its volume.
D = W / V
So 2.2 cubic centimeters of powder that weighs 1.9 grams has a density of 86.4% of water. You slap the label on the can and when you buy the next one you measure it and adjust your load accordingly. I know--it's metric---but---it's really quite easy these days with digital scales that weigh in grains and grams; you just need to be sure you're using the grams setting for this.
"If the enemy is in range, so are you." - Infantry Journal