Hi Jacob, there are rifled slugs, also known as foster slugs, and sabot type slugs. Rifled slugs are meant to be fired from a smoothbore barrel. This is most likely what you will want. Rifled slugs have slightly angled grooves on the side of the body. Karl Foster originally invented them. That’s why rifled slugs are sometimes called “Foster slugs.” They are designed to be fired through smoothbore shotguns (barrels without internal rifling).
Sabot type slugs are meant to be fired through a rifled barrel.
Unless you have a dedicated rifled slug barrel, you will want to use rifled, or foster type slugs.
Stay safe & have a great day!

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ed c there is also the Brenneke Slugs In the 1890s, Wilhelm Brenneke of Germany introduced the Brenneke slug. The most significant difference compared to the American Foster slug is that a Brenneke has a wad attached to the projectile that remains with it during flight to aid in stabilization.
The Brenneke is also solid, whereas the Foster is hollow. This feature keeps the Brenneke slug from deforming too much on impact, leading to deeper penetration. The downside is that its unique features limited the Brenneke slugs to short-range usage.

" A Foster slug, invented by Karl Foster in 1931, is a type of shotgun slug designed to be fired through a smoothbore shotgun barrel. The defining characteristic of the Foster slug is the deep hollow in the rear, which places the center of mass very near the tip of the slug, much like a shuttlecock.A rifled slug’s grooves may help it align correctly with the barrel throughout ignition. More importantly, the grooves allow the slug to compress. This allows it to safely pass through a muzzle that is outfitted with a choke tube. A Foster slug is technically its own thing, but most rifled slugs also qualify as Foster slugs.. Sabot Slugs are smaller diameter slugs encased in plastic (sabot) and are designed to be shot through "rifled" shotgun barrels the sabots fall away after muzzle exit

Hi Jacob and welcome. Foster type slugs are normally recommended first in smooth bore shotguns. Foster type slug is on the right. targetbarn.com/broad-side/sabot-slugs-vs-rifled-slugs/ -------- Cheers and stay safe!