Navarro, I don't know if you reload shotgun shells,
but there are some recipes that will suite your efforts just fine.
There are wads that hold the pellets in tight, and they work well from sawed off barrels. That will save you the grief of battering your gun apart with modern defense loads.

Of course, that kind of is the opposite of what an 18" shotgun was created for. They provided increased margin-of-error, back in the day.

Out there doing it best I can.