Did a search and couldn't find anything on this topic, though that surprises me so I am open to the possibility this has been discussed before.
Anyway, I am currently running an 870 for HD, with #4 buckshot in the tube and 00 buck on the side saddle. I have previously run all 00 in the past, but was convinced to go with #4 based on the suggestion of some local trainers that it has sufficient penetration while reducing the chances of missed shots injuring bystanders in a suburban setting.
I have a .45ACP service pistol as well as my carry gun handy. The 870 would be deployed in a stationary role only; covering the door while the police make their way to me. Any investigations of bumps in the night fall under the purview of the .45. The house is one level, so the possibility to shoot down stairs or have a reliable backstop is not there.
Finally, a semi-automatic rifle is out of the question; they are highly restricted in my state (NY), and 10 rounds is the magazine limit which in my opinion makes them substantially less useful compared to a shotgun. I am well-aware of the performance of 5.56 in drywall, but alas I believe the 870 is the best choice for my situation.
What is the current groupthink on #4 buckshot for home defense use? Go back to the 00 or is my thinking here good?