I'm looking at another 12 because I have bookoo 3" slugs, from Federal Tru-Ball to Dixie Terminators! ha. I shot just "one" Terminator from my HD (it has the smoothbore shorty bbl but with a magazine extension, and the butt has been shortened, but has a Limbsaver pad) It was still a face full, ha.
On the other hand, I have thought long about a 20ga Express with RS rifled barrel. There are many full bore size slugs available for the 20 now, i.e. Brennekes,etc. Years ago, my first 12 3" Wingmaster had a Mod, VR barrel. That thing could hit a coke can at 75 steps with plain Remington slugs! I kept "short shucking it" though, hunting rabbits with beagles, so foolishly traded it for an old High Standard auto "Deer special". It was a 20" smoothbore Cylinder with RS, and with #7 1/2s was an awesome brush gun on rabbits and the occasional woodcock! It was a jammomatic though, and off it went.