Quad loading is a technique used in loading shotguns. The technique works by holding four shells in your hand and loading two at a time. This technique speeds up reloading times and also looks cool. You have seen this technique if you have seen the movie John Wick 3. You can view a technical explanation from a professional shooter here.
I understand that the reloading time of shotguns is supposed to offset their power, but I would argue that in the grim, dark, war filled future someone, somewhere has figured out how to load a shotgun faster to get more dakka. Not to mention that even with this technique, it will still be a slower reload than a gun with a magazine.
If the devs want to be extra cool and score more internet points, place the emergency shell holder on the side of the shotgun near the ejection port that allows a player to hold one shell in reserve for a quick load. You can see an example of this emergency shell holder in both prior mentioned examples.
-This shell could be used by a player by pressing the reload button, while holding alternate fire and then pressing the fire button again
- A little animation showing the player popping the shell into the ejection port and then holding the gun ready to fire would happen when doing this combination
-This shell holder could be reloaded by pressing the reload button again after fully reloading the gun