I use a 12ga with a fully rifled barrel... it's a Mossberg model 695. I have spent an absurd amount of money fueling that gun... sabot slugs currently sell for about $3 a piece.
I decided that this gun is my designated SHTF firearm, as it is accurate, packs a punch and needs minimal maintenance... but ammo cost was a problem and I wanted to have a good pile stocked.
After a bit of research, lots of emptied shells and a bruised shoulder, I have finally found a reasonable (and affordable) solution...
Brenneke KO 2 3/4" 1oz. rifled slugs.
After learning that these rifled slugs could indeed be used in a rifled barrel, I tried the Brenneke 3" Magnums -OUCH! So, i bought several boxes of the KO's at $4.89 per box and was pleasantly surprised.
I tested them at 70yds... consistent 2-3" groups and I could shoot them all day without breaking my shoulder or bank account. I had one issue with the shell ejecting, but it seems to have gone away.
After many, many shells, there was hardly any lead fouling in the barrel... hardly anything at all, actually... very clean.
So, for all you folks with rifled barrels, who are tired of spending a fortune on sabot slugs, have no fear. You can affordably stockpile ammo for your slugger... you can, in fact, affordably just shoot it for fun!