Hello all,
I wanted to share my final comments regarding my conclusion on the issue of over penetration of a bullet when using a AR15 as home defense in hopes that this helps someone else.
Initial problem:
If I miss shooting the intruder with the AR15, the bullet will go through multiple walls and possible exit the house and harm my neighbor or kill them.
Research Results:
1. Yes, its possible for a 223 caliber (or handgun caliber) bullet to exit to shoot through walls.
2. If you want to use AR15 for bullet with least penetration, but still, enough penetration to totally stop an intruder, you have to select the right bullet.
Best Choices for Self Defense Ammo This link will guide you. For my case, I have a 1:9 twist barrel, which means my rifle will stabilize a bullet from 55 to 62 gr efficiently. Now I had to select the right bullet for home defense that will penetrate 12" of flesh to be fatal. In order for that to happen with my rifle I had to choose a bonded bullet. Bonded meaning the bullet can shoot through walls or glass, etc and still penetrate 12" to be fatal. I decided to buy the 223 Hornady Critcal Defense for home defense. And the Federal and Speer 62gr bonded bullet. Two magazines with Hornady and another with Federal/Speer. Done. If the situation get ugly in the house. I go to the AR15. If you have the 1:8 twist you can get the 73gr Critical Defense.
3. I had to learn my back stop if someone comes in my house. Where will I go to shoot, so if I miss the bullets will not leave the house or exit on brick.
After all this research, I decided my primary home defense is a shotgun with #6 birshot, because I can handle this better and for my situation, I don't have to worry about shells leaving the house. For me, its just easier this way.
However, the AR15 is right by my bed as well, just in case things get ugly.
Next is to practice and total harden the security of my home. Which I already did.
So, should an AR15 be used as home defense. Yes, but it depends on your house geometry and your back stop. If you miss, make sure the bullet will not leave the house. Unless you live in the country.
Thanks all for the help