Another good choice for the SHTF / Home Defense is a Remington 870 Express. Can be easily modified to hold additional rounds and with its shorter 18.5" barrel is good for close(r) quarters defense while inflicting maximum damage. Easy to find for under $300 also.
Two different weapons for two different purposes, but then I'm a "right tool for the job" kinda guy. ;-)
An 870 will never let you down. If you can afford it, pick up the M1A in the SOCOM variant. Bought one for my son and am kicking myself that I didn’t keep it for me.