IF I was going to "saw off" another shotgun, it would be a DOUBLE BARREL 20 or 12-gauge with about 10" tubes & a handgun-like rear grip.
(Back in the far away days when dinosaurs roamed Planet Earth, I was a town marshal & "fell heir to" a "cut-down" Parker 20-gauge DB with 8.5" tubes, that the previous marshal got somewhere. - Other than a few times on the range, I never fired it a single time BUT "combatants" just seeing it STOPPED numerous brawls in the "joints out on the county line" W/O bloodshed.)