I have a Carlsons rifled choke for a 20 gauge 870.
With my limited 2 years rifled choke experience I've noticed slightly better grouping with Round ball / wad -ammo, compared to any or no plain choke. I have two ball sizes, a tight fit is better. I get 6" / 75 meters with my "Economy RB:s" , factory trap ammo cut open, remove shot,add a cork and a round ball. Roll crimp while squeezing tight.
It's okay plinking ammo up to 50 m for me.
I do get better results with fullbore slugs like this Zveroboy, a typical 25 m group, fired standing with a red dot / 20 gauge 870. I'm only in the beginning of testing these further out from bench, a 12 gauge fullbore / fully rifled barrel madness caught me. 20 has been on standby...
I think fit is king here,too. And how the wad grips the slug to spin it, my coated slugs/balls may not have the best grip...
Fullbore has less variables.
Here is rifled choke 25 m standing. Fullbore Zveroboy.