Now we are talking.
This is my kinda thing.
The more you handle your shotgun the better off you will be, so anything from bunny rabbit hunting to clay games will make you a better defensive shotgunner. Your shotgun should be an extension of your body.
If you can find yourself a local 3 gun or tactical shotgun match. That way you can practice tough scenarios on the clock and under pressure. Some people may say, but that is unrealistic, when am I ever going to engage 22 bad guys with my shotgun. Guess what? If you get to the point that you can engage 20 of them super fast, then one or two should be downright easy.
The best way to practice is get some steel targets. This is really the only way to go for good shotgun practice. Card board boxes, grocery bags, and milk cartons will work too, but they don't work nearly as well as a good steel target. Access to a timer will really help you improve, because the timer doesn't lie.
Practice hitting a single target as fast as you can. When that becomes as easy as breathing, add more targets. Space them close together to practice hammering out rounds quick. Space them further apart to practice transitioning from target to target.
Practice shooting the targets multiple times quick. If you have falling steel, practice to the point that you can hit them more than once before they fall down.
Change distances. Change positions. Shoot from standing, sitting, kneeling, and since you are using a pump gun, especially from prone. It can be done, but you need to figure out how to do it well. Practice with your off hand. Practice from around corners, doorways, over cover, around cover, under cover.
When you get to the point that your shotgun is really your friend, practice moving and shooting. Move laterally and engage a bank of targets. Charge the targets, retreat while shooting. Just be careful when you do this if you are using steel targets, because the closer you get the more you are going to get pelted.
Trust me I know on this one.
For the high volume practice you don't need to use expensive defensive ammo. If it costs too much, then you won't be able to keep it up. That defeats the purpose of training. Use cheap bulk stuff like the Winchester big packs that they sell at Wal Mart. But at the same time, make sure that you can still be fast and accurate with your good stuff.
Make sure you pattern your defensive gun with your choosen load at various distances. It can be very eye opening. Memorize those patterns.
If you believe in slugs, you need to practice with them as well. Shooting shot at man sized targets fast requires a totally different kind of focus than making a precision shot with a slug. When I'm shooting shot I don't really use the sights at all, I focus on the targets. When I shoot slugs I have to shift gears and treat my SG like it is a rifle. Learn how to select slugs and change loads if you need it.
Practice keeping your shotgun loaded. Learn to manipulate the shotgun in a manner that if you ain't shooting you are loading. Find the method that works best for you to do this. If you need to go to an awkward position to effectively load the shotgun then you are doing something wrong. Some people may need to build up their upper body strength to the point that this is easy. You should be practiced enough with manipulating and loading your SG that you don't need to look at the gun to do so. Keep your head up and scanning.
For scenarios, use your imagination. There are lots of good ones. If you would like I could go back and look at some match results, describe the stage to you, and give you and idea what some good times would be.
I had a stage a couple of weeks ago with 22 steel targets and a whole bunch of movement and use of cover.
www.udpl.net/results/3-Gun/111503s1.htm I did it in 31 seconds.
I figure if I need to engage a couple of home invaders, I'll be a bit better prepared than your average gunnie.
Finally your shotgun should be your friend! Remember if you aren't having fun, then you are doing something wrong.