May be light, but 220 grains is all the 10ga. hull will hold.
Commercially loaded 8ga. blanks are 300gr. of 1f.
The National Civil War Artillery Assoc. website (
www.ncwaa.com/Powder.htm) is very explicit in not using anything finer than 2f (ffg)
They state that a proper blank load is 1312.f grs per inch of bore, so assuming an 8 ga. at 3/4", their suggested load is 985 grains. A 3 1/4" 8ga. hull only holds 300 grains, so they obviously must be referring to muzzle loaded cannons. (unless the illusive 9 3/4" 8ga hull is out there somewhere)
I can say that a 300gr. 8ga is a LOT louder than a 220gr. 10ga.