Note from this chart that Tatham & Bros of New York was the size eventually adopted as Industry Standard. A size "B" is .170" diameter. subtracting the shot size number from .170" of all smaller sizes will give the diameter of that size, just remember to put the decimal at the proper place. for examples .170 - .05 = .120" for size #5 while .170 - .075 = .095" for size #7˝.
Number per ounce will vary slightly dependant upon exact alloy. I believe the numbers given in Drew's link are very near pure lead or "Soft shot". So called "Chilled" shot will have slightly higher numbers per ounce.
