also live in 1 br apartment.
with one neighbor along the kitchen/bath wall.
I keep mossberg 500 20 gauge with #3 buckshot.
main reason is from my BR door down hall toward main (only)
entry is a straight shot facing due west.
neighbor is due south.
also, behind the entry door is 8 feet (walkway) and then a brick
facade / roof of the adjoining bldg but NO apartment unit there,
just a couple of rails / AC units. So no people and a brick backstop.
From inside 25 feet, I would have no problem using #8 shot (bird)
or # 4 shot (have a few boxes of this called 'heavy turkey').
I've seen the #8, the #4 and the buck shot damage to plywood sheets
(6 deep) from 15 - 40 feet. Any of the 3 will cause an intruder(s)
problems. The buckshot delivers more penetration (of course).
"It'll happen fast once I start" - Charlie Waite