In that I don't have a life, I searched thru a number of my books today!! Finally in the little 64-page booklet titled Shotgun-ology by Capt. Chas. Askins, A Handbook of Useful Shotgun Information, published by United States Cartridge Co. in July 1926, I found an answer. On page 58 is a table of buckshot numbers (Eastern Size and Western Size), Diameter in inches, and number to the pound. Eastern No. 3 is Western 8 or 9, .25", and 299/lb. Eastern No. 2 is Western 7, .27" and 238/lb. Eastern No. 1 is Western 5 or 6, .30", and 175/lb. Eastern No. 0 is Western 4, .32", and 144/lb. Eastern No. 00 is Western 3, .34", and 122/lb. Eastern No. 000 is Western 2, .36", and 103/lb.
There is an * next to the Western Size heading and the footnote states "Western Size markings are now being discontinued and all American loading companies are standardizing their Buckshot loads on what have hitherto been known as "Eastern Sizes.""
