The rifling built into the slugs is partially to spin the round, and partially to compress through the choke. I've shot rifled slugs out of my modified choke in the end of my 26" 870 barrel and didn't have any problems. Just make sure you aren't shooting Sabot slugs out of a choked barrel. I'm under the impression that MOST chokes are okay for rifled slugs, but would be careful to make sure you don't have some esoteric choke like the square duck choke.