I found severl charts of the different shot sizes from the New York, Baltimore, Chicago, St Louis, etc. in books by Money, Leffingwell, et al. But, it took quite a while to find that chart on buckshot.
In Guncraft, by William A. Bruette, copywrite 1912, there is a size chart that gives the number of pellets per ounce of shot from Tatham Brothers, New York; Le Roy Shot & Lead Co., New York; Colwell Lead Co., New York; Chicago Shot Tower Works, Chicago, Ill.; Sportsman's Shot Works, Cincinnati, Ohio; Omaha Shot and Lead Works, Omaha, Neb.; Thomas W. Spark, Philadelphia, PA.; and The James Robertson Mfg. Co., Baltimore, Md. Just picking one shot size, #7, the number of pellets per ounce were -- 291; 286; 291; 363; 323; 291; 338; 323; 305; and 350.
