Now I realize that everyone will have their own preferences and opinions, but the gals and I have multiple sets of three types of firearms at the ready for our home and personal defense... pistols, Ruger SR9 and SR9c... rifles, Ruger Mini-14... and shotguns, Mossberg 500. We have many years of experience with these particular firearms and our guns have all been run fairly hard, well-maintained, and demonstrated excellent reliability.
While the guns are reliable and have different strengths depending on the situation, the gals and I need to practice regularly to be as reliable as our guns. It's been a busy summer, the excavators are reconfiguring our shooting range out back, and I'm recovering from some significant surgery... so I've been doing a fair bit of dry-fire practice and reloading drills with dummy rounds.
Our home-defense Mossberg 500s have TacStar six-shell side-saddles for tactical reloads of 12-gauge buckshot or slugs. There are various views, techniques, and opinions on tactical reloading with shotguns, but basically there are two primary methods most folks use involving keeping the shotgun up, shouldered, and in the fight with the strong-hand while the weak-hand loads additional shells.
The first method is done with the shotgun shells loaded in the side-saddle pointed down so the shooter removes a shell by pulling it up, then reaches over the top of the receiver and drops it into the open action through the ejection port.
The second method is with the shotgun shells pointing up in the side-saddle. The shooter then pulls a shell down from the side-saddle, reaches under the gun and pushes a shell into the tube magazine with the thumb while the action is closed.
I've exaggerated the moves in the pictures so you can actually see the shotgun shell. You'll also notice that in the final picture, for our standard set-up, we keep four additional shells of buckshot pointed down and two shells with slugs pointed up. This allows for tactical loading of additional buckshot over the top of the receiver and what I might call "strategic" loading of slugs as needed from underneath into the tube magazine.
So if you decide to use or integrate a shotgun into your defensive plans... however you use or configure your shotgun for home or self-defense... they have limited round capacity... so practice tactical reloading and maybe consider some... Side-saddle shell shucking...
Update: I probably should have mentioned that the TacStar Side-Saddle shell carriers were easy to install and have held up well over time. They come with all necessary hardware and screws... just use some medium thread-locker on the mounting screws... which I often do on most guns.