We were 100 percent agreed a shotgun is the best weapon. We mostly agreed on why. We had a difference of opinion of one item regarding the shotgun. That in a moment.
Why is the shotgun the best?
1) Loud. When you pull the trigger, everyone knows.
2) Easy to use. A shotgun has the quickest learning curve of any firearm.
3) Max damage.
More critically, a shotgun blast delivers significantly more damage than any other home-defense sized weapon per shot. I can't find it - dammitall - but I read a piece about the "stopping" power of various handguns from a .22 through a .44 mag in police and self-defense firing situations. Surprisingly, the little .380 was a top performing round.
Not surprisingly at all, the 12-gauge in home-defense distances blew (pun intended) everything else away.
With Federal Flitecontrol 8-shot 00 buckshot (THE recommended round for home defense), one shot is all that's needed. Get the 8 shot. Do not use the 9 shot. In 9-shot, one of the lead balls turns into a flier because of the way the projs are placed in the shot cup. 8-shot, all stay on target.
ONE v MANY
Look at this way.
In a handgun (or rifle for home defense if you have no sense), with each pull of the trigger you deliver 1 bullet.
In a shotgun with buckshot, you deliver a BUNCH of bullets per shot.
Someone now is going to talk about hydrostatic shock.
Yep. 1 .44 mag round delivers far more hydrostatic shock than a single buckshot. Every time.
But 8 buckshot at home defense range covers an entry area from a softball to a small plate. Each shot creates a separate wound channel and a separate shock channel. The total area affected is much larger with the 12-gauge than the .44 mag.
You can shoot someone 8 times with a 9mm in a 4-inch group. You can shoot once with a 12-gauge and accomplish the same thing.
4) If you get the Law Enforcement or low recoil buckshot, your chances of over penetration drop dramatically as compared to big-bore handguns or even mid-bore handguns with hot loads. If you use a rifle for home defense, please make sure you live several miles from me.
Also, high penetration rounds, like FMJ or solid brass are NOT SUITABLE for home defense. You do not want your bullets flying through several walls. The good stuff starts around 2:30 -https://www.youtube.com/watch?v=DYLbmSp5itA
5) Do not get one of the shotguns with a 10-round magazine tube. Why? Too f'danged heavy. 3 shots are enough for home defense. Get a short barrel too.
So what did Mike & disagree about?
Sound.
https://www.youtube.com/watch?v=B2Gz-A-XO8w
Sez me - When I rack that gun, I have done several things. I alerted the perp in the house that I am armed. I have told said perp he has 2 choices, leave or die. If the perp leaves, situation solved for me. If he keeps coming, I am committed to killing him.
Sez Mike - By racking the gun, you tell the perp where you are. By running him off, you have not solved the problem so much as you pushed it off probably on someone else.
Mike is correct. However, on the position issue, it's my house. I know the layout. The perp does not. I have the advantage there. I do not like the idea of having the thug run away to possibly harm or kill someone else. But if he runs away, I also eliminate the risk of me and my family being harmed.
The paperwork is a lot less too.
ONE WARNING
In the words of Mike, "Shotguns are not drop safe. People get shot every year from a loaded shotgun falling from a corner in the house/propped against the truck/leaned up somewhere. Your scattergat is not safe with a round in the pipe, and propped next to the bed. IMO, if you want to be safe, you have to rack the slide and put one in the pipe, in the event of an intrusion. Thus, making the 'to rack or not to rack' a moot point."