First I don't recall Ever hearing of a shot string as long as 25-30 feet at 30 yds nor one as short as 2 feet at that same range. To Summarize Burrard's work in which he reported on some of the most extensive work probably ever done on shot stringing his general conclusion was unless you are shooting beyond 40 yds, treat it as if it didn't exist. Don't lay your misses on shot string. This also was all accomplished with bare lead shot fired from a shell loaded with card & felt wadding.
It never ceases to amaze me how many people start Shoutng about the "Square Load" & then totally fail to follow it in their load recommendations. The exact area occupied by a given weight of shot will of course very depending upon both exact alloy & shot
size. The weight of a bore fitting lead ball is of course readily obtained by simply dividing 16 by the gauge number. A very close approximation then of the weight to make a Square load can be found by multiplying that weight by 79%.
To the nearest 1/16oz then square loads are 10ga = 1 1/4oz; 12ga = 1 1/16pz; 16ga =13/16oz; 20ga = 5/8oz, 28ga = 7/16oz & the great Big .410 (67.49gauge) = 3/16oz.
Would someone now explain very carefully (Please Write Slow, I don't Read Fast) why if a .775 long shot column is OK, even ideal, in a 10 ga it is necessary to drop the length of column to .550" in a 28ga. Did you ever notice how the different gauges tend to have shells of near identical lengths. hat's because the shells were built & designed around loads having near identical lengths of shot columns. Thus the smaller the gauge the more "Out of Square" the load tends to become but performance is not really adversely affected. 1oz of shot has a lesser extreme range than does 1 1/4oz assuming same choking for both, whether fired from the same gauge or a smaller gauge.
