Good morning Daryl,
Yes indeed, in the old days a Lot heavier shot charge was often used than today.
I know Hawker tells us that for a 14 -23 bore, an ounce and a half of shot, and in this he was also recommending a square load....and this charge varied by the shoulder.
I wasn't finding any fault with what you said, just that today we often hear of more powder being used in relation to shot, and this blows patterns.
My little old Lofley double 20 passed the bean tin test at 40 yards with English no 4, (about 5's here) and always patterned well at that range with 2 drams and an ounce and a quarter.
The list of charges up the page was for breechloaders.
The lightest setting I have ever seen on a shot flask is an ounce, then an ounce and a quarter. this size is also the most common, followed by 1 1/4 and 1 1/2 ounces.
All the best my friend,
Richard.