The accepted distance a knife wielding attacker can cover and deliver a killing blow before you can draw and fire a holstered gun. (note: YMMV)

That pretty much defines the distance that you can defend your use of deadly force after the event.

But to respond to the thread topic, I use an AR variant for home and property protection. With a couple of AR-16's To choose from, one with a laser and one with a bayonet (for up close and personal) I most usually chose my 300BLK Sig MCX with laser and light.

The sub-sonic rounds have good penetration, but in the back I have a shooting range and my nearest neighbor to the right is half a mile away. To the left is a concrete garage, a good back stop for any 30 caliber rounds going through the walls of my home.



It's folding stock makes it very short for discreet carry, and handy to put behind the seat in my pick-up truck. Still pretty loud to cap off indoors (or from the cab of my pick-up) so I'm planning to get a can for it, and maybe even a SBV (pistol?) to keep it handy with a suppressor attached.

Or on the tripod for sustained fife:



digiroc