38 Super is .356 and you can find factory ammo loaded with the appropriate size bullet. If you reload, you can get .356 from Precision Delta for a good price. The 38 Super cartridge is identical to the older 38 Auto/38 ACP. The Super is basically a +P cartridge. The older guns could not handle the increased pressure, thus leading to the Super designation even though the cartridge dimensions are the same. I have an old Colt 38 Auto that I reload for since you cannot find the lower pressure 38 Auto ammo any longer.
A well regulated militia, being necessary to the security of a free state, the right of the people to keep and bear arms, shall not be infringed.