For those interested in the math the volume of a sphere is Pi x D cube / 6.
For a cylinder having a length equal to its diameter it is Pi x D cube / 4.
The cylinder thus has 1 times the volume of the sphere.
"However" the sphere is solid with no air space, the cylinder filled with shot has a lot of air space around the individual pellets. It works out the normal "Square Load", dependant upon exact shot size & alloy, but still talking predominantly lead, has a weight of around 75% - 80% that of the pure lead sphere by which the gauge was determined.
There has never been a shotgun built, regardless of gauge, in which the round ball equivelent & the "Square Load" were of identical weight. It is essentially impossible with any shot size of a useful nature.Not sure how small one would have to go, but likely even smaller than the #12's used in some .22LR "Rat Loads".
