lexofer said:
Using a cylinder choke will keep the choke threads from fouling and won't cause any constriction issues as the slug passes through. I actually get the best groups from an IC choke in my gun. Shotgun slugs are usually made of soft lead and have "rifling" which are little fins that easily deform as there isn't much surface area in contact with the barrel. I've shot well over 1k slugs through an IC choke and a few dozen through a modified choke without any issues. I've seen a lot of varying opinions online about shotgun chokes and slugs but that is my personal experience.
The rifling on these slugs doesn't really do much to stabilize them. They are primarily stabilized by the fact they have most of the mass up front and the backside is a hollow skirt like a badminton shuttlecock. I get about 3"-5" groups at 100 yard with cheap slugs using just a vent rib with bead front sight. Offhand in the field I probably wouldn't take much more than a 50 yard shot but if I had a good rest I'd feel comfortable at 100. Make sure you are looking straight down the rib, can't see either side of it or the top, that will help line things up the same way you would if you had a rear sight.
Main thing is test out your slugs to find out the hold at various distances and to check that your barrel is straight. A lot of factory shotguns do not shoot true, they'll shoot slugs off to one side or the other which can be significant with longer shots. The holds for my Benelli is about 8" high at 50 yards and 14" low at 100 yards.
I've patterned lots of different buckshot and the majority don't reliably keep most pellets on a man size target past 30 yards. Use buckshot with a flight control wad if you're going to be shooting at 30+ yards with buckshot. Flight control wads keep the shot together a lot tighter than chokes do and you can easily switch between slugs and buckshot without having to change chokes.
I could have googled, but this is why I TexAgs. Thank you!