Pretty hard to beat 00 buckshot (9, 12, or 15 pellets). Generally, slugs aren't desirable for home defense, since they can go through walls and still have enough power to seriously injure someone, but there are some fragmenting slugs out there that partially solve that. Also, there are some "buck and bullet" loads (Winchester PDX1, for example) that may be the best man-stopper, but you still have the concern of collateral damage.
00 buck. It has been used for a very long time and is used in Iraq and Afghanistan. Not to mention countless Police Departments. I don't bother with slugs or boutique loads, i don't see the need. If I want a rifle that is what I would pick up.
Shotguns are king up to 50 yards beyond that a rifle is a better tool. Keep it simple and you can't go wrong
It does depend on the nature of the home you are defending; nature of construction, free-standing or adjoining walls to other homes, distance to neighbor if free-standing, room dimensions, floor plan, occupants. 00 buck will penetrate most interior and wood-framed walls pretty easily and if you might be firing toward a wall that has your children, spouse or neighbors on the other side, it might change your optimal load. If there is a chance that you are going to have to cut loose toward an interior wall that might have occupants on the other side then birdshot penetrates less. Nonetheless, at close range it still ends up devastating when hitting an invader as basically one mass of lead.
As advised to me by the Durham City Police Dept. in NC, use No. 4 Buck. It is small enough to reduce over-penetration inside the home yet powerful enough to ruin your day. It's spread is such that you increase the probability of hit(over 00) and... in a more morbide way, you aren't going to get fixed after taking a load of No. 4 Buck! They can't fix you after taking a shot of it, there's too much lead spread over too large an area for them to be able to put you back together.
However, No. 4 is expensive and hard to get, at least for me. So, Field loads such as 6 shot are very effective within typical room/hallway distances! Want to test it? Set up some pumkins or water melons at 10 yards and pepper 'em with 6 shot, you'll see. As stated here, slugs are less then ideal! Too much lead moving too damn fast for inside the home. 00 Buck is great and will do the job, but it may not be the best option.
NOTE: Yes, 7 & 8 shot within room distances is enough to ruin the hell out of the BG's day! At this distance, the wad hasn't seperated from the shot... you basically are shooting a frangible slug! However, once the distances gets to about 10 yards(depending on barrel) you have reduced the effectivness quite a bit. Will it still hurt? Hell yes it will... but it may not be enough to kill the BG. With that, it may still be enough to stop the BG... mission accomplished, no?
This sucks, I just watched a video on the most destructive/effective 12g... I can not for the life of me remember exactly what the ballistic jell results were but it was something like 00 with the pellets the size of 380 rounds or single 0 with the big pellets. Basically the most destructive was with the biggest pellets other than a slug that you can get.
That's what happens when you watch hours and hours of youtube videos
I use #4 and High Brass 2 3/4 inch rounds in a mossberg 500.
Can you say trainwreck boys and girls?
At the longest distance in my home the shot pattern does not spread enough to not be devastating.
An once and a quarter of lead moving as one fluid entity at the speed of heat is bad juju on any home invader.
for in the building engagements, I have low brass #8 birdshot in my SGs.....for an engagement upto 25' I have #4 buck and 000 buck...all 2.75" rounds. AND YES, low brass birdshot WILL KILL easily at 20 feet. go onto YouTube and look up Demolition Ranch's birdshot vs buckshot vs slug video.
and for those who rant about that birdshot is NOT an effective killer.........just shoot some!!!! I have shot 2000+ rounds of shotgun shells while hunting and testing shot patterns, penetration, ect., ect......and a load 1&1/8th of lead shot going 1200fps with do lethal damage to the chest of a target enough to stop the target WITHOUT shooting through walls and killing a bystander in another room.
one test we did was walking through a house that was going to torn down and shooting pumpkins with both buckshot and birdshot in the rooms. the buckshot penetrated one wall and entered another room almost everytime, where as the low brass birdshot didn't.