I am not sure yet which muzzle attachment I would use.
The use case for the shotgun would be in my house or around outside (I live on 20 forested acres, but there are houses that are well within range of a rifle or handgun) and possibly at night. I would also want to attach a good flashlight and maybe a laser combo - like the Surefire.
So it would probably be a flash hider - if it was effective - to tame any flash in the dark.
This particular shotgun is a bullpup Mossberg:
View attachment 97247
I have removed the foregrip - I didn't like it. I also disable the grip safety.
It is heavy so recoil is moderate. I would probably go with an extended mag, which may or may not mean the barrel would be longer. If I stick with the current mag (6 shot IIRC), then I would not want the barrel to be any longer - the whole idea of a bullpup being its short length.
I usually take either a semi-auto or revolver and powerful compact flashlight out when looking to see what is wandering around outside setting off my motion detector lights, but I can foresee scenarios where I might want to also take something more powerful.
Usually it is just a neighbors dog, but we have had black bear and cougar wander through too. Not that I would shoot them just for that, but if they were surprised...
Also, neighbors sometimes put out their garbage cans the night before collection day (although they are pretty good about not doing that - in the winter they do it in the morning when it is dark). Usually we have had no problems with bears and garbage, but that could change.
We have had no problems with tweakers, but you never know, and it is best to be prepared.
This is not something I have to do right away - I just have been wanting to mod the shotgun to make it a bit more useful for its intended purpose. I got it a long time ago for about $300 so I can afford to put some mods on it. I have looked at the KSG but I am not sold on its reputation (not a big fan of Kel-Tec), and so far the other bullpup shotguns available here don't have a good rep either.
Now if Benelli would make a bullpup M3 Super 90, that I would buy.