Doesn't matter what size shot. This is volume measurement. That is why there is a given number of shot in a modern shotgun shell that goes up and down depending on the size of the shot. A 1oz load of #8 shot will have more pellets (or pieces of shot) than a 1oz load of #5, which will still have more than a 1oz load of #2 or BB, and so on.
Don't mix up weight and volume. Especially between ounces and grains. By weight, 1oz is 437.5 grains
The trouble is, the chart already mixes weight and volume.
The chart notes a given volume powder measure holds a certain weight of shot. Shot is measured by weight as I noted above.
The trouble is, if one gets too technically minded, a 'given' measure will only throw X grains of a certain powder, depending on it's granulation size and specific gravity)
That measure will not throw the same weight of shot in size 5 as it does in size 7 1/2.
That I think, is why R.J. Bruce asked the question.
However, the chart works fine for "rough" work with a smoothbore without the counting of pellets for exact pattern percentages.
The same goes for powder charge testing. We go up and down, and when we find the volume measure that works best, we (I) weigh the powder that measure 'throws', so I can make
another 'perfect' measure for 'THAT' gun is I lose the "best" one.
Same goes for shot - we use a bunch of different 'thrown' measures for powder and shot and when we find the one that works - we use it.
Some of us like to know what that powder and shot "Load" weighs, so we measure it. Some even count pellets in, and pellets on the paper.
All about "degrees" of accuracy. Some care, some don't. Good thing we are not all alike - THAT would be boring.
I might add here, that by 1850, THEY were counting pellets per ounce for the different sizes of shot. #'s and %ages were used in field trials for testing guns and their shooting qualities.
That "data" is available in W.W. Greener's 9th edition of "The Gun and it's Development". Book #1 of "The Gun and it's Development" was written by W. Greener in 1855.
It's a good read!