My 40-year old Remington 870 is an unusual piece, having a 21" barrel with choke tubes. It has the standard magazine tube, accepts 4 rounds (2 when I put in the plug for duck hunting). At home it stays loaded with 2-3/4" loads of BB shot with the improved cylinder choke tube. I doubt anyone will notice the difference between 1.25 oz. BB shot and buckshot from one end of the house to the other end. I also doubt that the BB shot will penetrate more than one wall, which I find important in a residential area.

If the 4 rounds of 12-gauge aren't enough I will have to use the back-up piece, a .45 caliber pistol (8 round mag).

No, I don't feel under-gunned.