Did anyone besides me ever wonder about those markings on the old shot & powder dippers. Note on Erics dipper it expands to twice its size on the powder from 2 drams to 5 drams, but on the shot it goes from 1oz to 2oz. If the powder doubled why did not the shot stop double to 2oz also. This seems to be consistent with nearly all the old dippers I am familiar with. I have concluded the answer is to keep things "Even" they usd dram & 1/8 oz settings. At the base line though it takes 10 of the drams to equal 2 but only 8 of the 1/8 oz settings to equal 1 oz. My personal belief is that the 2-1 is essentially correct & the powder settings are pretty accurate, but the shot charge gets a bit light with each setting as you go up to a larger measure.
I tend to agree with W W Greener when he recommended as a general purpose load in the 10 gauge 4 Drams-1 oz shot, stating that when 1oz only was used the 12 gauge would handle it so well there was no practical gain in going to the larger gauge.