those 5/8-ounce 12 gauge shot charges must really be "square"!
A "Square load" definition is somewhat dependent on who is doing the defining. The one I feel is most correct is that the length of the shot column in the bore is equal to its diameter. In 12ga this gives an approximate 1 1/16oz load. Thus the extremely popular 12ga loads in days of yore of 1oz & 1 1/8oz straddle the Sq load. Loads for the smaller bores were seldom loaded "Square" but more often had a column length similar to the 12ga. A Sq load for the 28 by above definition would be about 6/10 (0.60) oz. (Note these loads were primarily developed to give desired ballistics at acceptable presures for the burn rate of available powders, thus the similar column lengths) If you check popular shot wts of older shells you will find they run very close to being proportionate to the Square of the bore dia.
Others have defined a Sq load as an equivelent wt to a round ball, but personally I would simply call this a round ball equivelent load, not a Sq one. Loads meeting this definition can be found by simply dividing 16 by the ga number thus for 12ga is 1 1/3oz & for 28ga 0.57oz or about 9/16oz.
I have read a lot of "Gun Writers" who put great stock in the load being Square, but can't recall ever seeing any "Real Balistician" give any weight to it.
The most hillarious thing I ever read on sq loads was a writer extolling the virtues of the 28ga because of its Sq Load. He proceded to give the rd ball theory & rightly dived 16/28 & came up with .57. He then stated this "Showed Conclusively" the 3/4oz load in the 28 was square. Don't know if he was totally dislexic or so mathamatically ignorant he just didn't know that .57 & .75 are nowhere close to being equal, in spite of using the same two digits, "OR" if he thought all his readers were that ignorant.
