spoiler: if you miss the bad guy, all calibers and loads go through multiple (5?) walls. If you hit the bud guy, HD loads of rifle penetrated the walls behind the least.
Regardless of the firearm selected, HP ammunition is a no brainer for HD. Even an AR should not be loaded with FMJ. Plenty of rounds for easy expansion out there. If chambered in 300 BLK, even better.
For Antifa? I like the crew served belt fed option mentioned above!
I find it interesting that over penetration is a concern with a 357 revolver but not an AR?
The 357 is pushing a bullet with a relatively large frontal area out at 1200ish FPS. The AR is pushing a streamlined little bugger that's quite pointy at close to 3000FPS.
To the OP:
What is your home's layout and size?
Do you share a wall with a neighbor?
Do you have a spouse/kids or do you live alone?
Do you have any training on firearms?
Do you understand the differences between "ball" ammo and defensive ammo?
Are you someone that can actually point the muzzle of a firearm at someone and attempt to destroy them?
No need to answer these questions in the thread. They are posted just to give you something to think about.
For me, I have a striker fired, semi auto pistol with passive safeties next to my bed with a flash light. It is loaded with defensive hollow point ammunition. Why? Because my home is small and my neighbors are close. HP's expand in walls and dump their energy into the plaster better than ball ammo will. When I miss my intended target with HP, I feel some reassurance that the bullet will stop in the wall/ceiling/floor before hitting someone that I did not intend to hit.
If I had a larger house and/or more land to "defend" I would consider an AR for home defense. But for my scenario, my choice makes sense to me. It may not make sense to or for you.
I have owned more than a few AR's over the years and have never considered them in a defensive role in my home. They are toys for me. I have a battle rifle, but it's not what sleeps next to me. It is, however, the gun that I would use my pistol to fight to get to if the time came. In the world, it's a very versatile tool. In my home, hard pass.
And, by the way, if you're simply looking for an excuse to purchase an AR, by all means have at it.