Using Jim's definition of a Sq load, & as best as I can determine, this was the original meaning, IE length of shot column in the bore equals it's dia, the following are "near" sq loads. Data derived from a reference table contained in Alliant's Reloaders guide giving length occupied by 1oz of shot in the various sizes of bores.
10ga = 1¼oz
12ga = 1 1/16oz
16ga = 13/16oz
20ga = 5/8oz
28ga = 7/16oz
.410 = 3/16oz
I once read an article in a magazine devoted to shotgunning in which the author was heaping great praise upon the 28ga based upon it's firing a Sq load. His definition however was that it equaled the weight of a round ball which fit the bore. He then rightly stated this weight could be readily determined by dividing 16 by the gauge number & stated the 28 ga round ball would weigh about .57oz. This he said emphatically proved the 3/4oz load in the 28ga was a "Perfect Sq Load". Fantastic!! My 4th grade Grandaughter knows that .57oz & .75oz is nowhere close to being equal even though they happen to share the same two digits (In Reverse Order). So much for the 28ga Sq Load & so much for that mag. That was the "Premier" issue & I never bothered to buy another.
