I wonder if they specified length of cartridge. I.E. If you have a shotgun that holds seven 3" shells, that same shotgun can hold 12 of these 1-3/4" "Minishells":
Aguila Minishell Ammunition 12 Gauge 1-3/4" #4 and #1 Buckshot 11 Pellets Box of 20 (Midway USA)
As dishonest as anti-gunners are, you KNOW if the shell length isn't specified, they'll jam shotguns full of these tiny shells, and promptly declare them illegal "assault weapons".
Nope, they didn’t. Read the whole thing. It didn’t specify how many rounds of what, or even that it be the round intended for the mag, just that it could hold more than 7.
Likewise, short shells in lever action rifles could also be used.