Research double stack mag's, that is what increased 9mm capacity.
You seem to not know the difference between bullet's and cartridge's.
A 9mm, 380, 38, 308, 306 ect.., are basically the came caliber "bullet'.
A 22 short is the same caliber "bullet" as a 223, or 5.56 military round.
The powder behind the "bullet" is what determines capacity of the weapon.
Mass times velocity equal energy.
Since 1975, I have always had my double action 44 caliber revolver as a wake up in the night defense weapon.
Totally reliable.
380 auto as my "truck gun".