I would give Remington Sluggers a try I used them in my Remington 1100 for a time they did well. It was rifled sights and rifled barrel. If they work great if not it really does pay to use a sabot slug something from Lightfield they are great. Ive spent countless hours and dollars and shoulder pain trying to find slugs that shot well Ive since gave up and use a 458 Socom AR and this year will try a .243 its so much easier to find a good load for a rifle but the best of luck in your search. I have found that most slugs are too fast for the rifling in most shotguns and they don't stabilize well Lightfields are a touch slower because of weight and are outstanding. Stay around 1500-1600 fps slugs that are faster like 2000 fps you get a lot of flyers
I found that some barrels foul more than others, people may need to test for cleaning interval (and also how many foulers to fire before going for group). I had very good results with WW HI Supremes in 3 different rifled 870's.
But when that slug was discontinued, so ended my rifled slug gunning days.
I don't remember what advertised MV was for those slugs, I always ran the 2 3/4" in my 3" chambered guns.
Did well with rifled Remingtons and sabots.
Smoothbore Remingtons never did well for me, one was mediocre at best.
Mossberg 500's smoothbore, 5 of them tested, did well with fosters. Markedly so over Big Green smoothies.
Back in the 80's it was kinda known to get a M500 over an 870 for deer hunting around here.
Old Remington sluggers were of smaller OD than Winchesters. They upped their OD later. I think a couple of yrs ago I saw some with the "new and improved" packaging. Suppose some old stock of the smaller OD are out there. Buy something off the shelf now, stores that move inventory....... should be of the better size.
I keep a 12ga bore snake in my hunting pack whenever Im using my slug gun (fully rifled Benelli SBE2) after 3 or 4 shots I run the snake it seems to really help.
My wife uses a Mossberg 500 20 ga. When she shoots slugs out of the smoothbore she uses Winchester super X. They are "deer accurate" to at least 50 yards, she doesn't shoot often enough to try shots any farther than that.