A shot gun can easily be used for self defense without the scatter. This is a trick that I learned from the SRT (aka SWAT) team at Ft Leavenworth, KS. Take a 3” shell with #6 or higher bird shot (#9 recommended). With a black felt tip marker, place six evenly spaced dots on the outside of the shell, between the top and the bottom of the wadding. Make three cuts with an exacto knife, connecting two dots and spaced evenly around the shell. Seal the top of the shell with wax or plastic so that it is smooth and level across the top.
When you fire the shell, the force applied to the wadding will tear the remaining side wall of the case and the whole case, wadding, and shot will leave the barrel as a single unit just like a slug.
However, upon impact, the front slows down and the shot will push out the side of the case. This will have the effect of distributing the entire muzzle energy within the first 6 inches or so of the target. Turn what ever meat happens to be a that location into jelly. If the shot misses and it hits a wall, the round will also fragment and will deplete much of the energy right away.
You can get an idea of the damage by shooting a gallon milk jug filled with water.
It also has the added advantage that the bad guys think that you wont shoot because of the shot gun’s scatter. The will often accept a shotgun’s presence in a hostage situation because they think you wont shoot for fear of hitting the hostage. If you put a red dot on the bottom of the shotgun barrel, you have a close in sniper shotgun.
That trick works (cut shells), but it can cause problems. I would only use it in emergencies. Another trick is to use a binder, such as wax or glue, to hold the shot together. You have to handload or be willing to open up the crimp on a factory shell for that system.
I would recommend that you buy some Federal flight control buckshot. It throws incredibly tight patterns at close range (about 9 inches at 25 yards) At 5 yards there is just one ragged hole.