Slugs and Buckshot in Full Choke Barrels?
Foster slugs, aka rifled slugs are nothing more than soft lead thimbles. Only the thin "skirt" area is standard bore size (nominal .730) and will swage down through any modern full choke (nominal .690 - .695)
Breneke style slugs have deep "fins" to compress through a full choke. This type of slug is usually made of a slightly harder alloy.
Single round ball loads are again being commercially manufactured, usually with a soft lead .65 caliber ball centered inside a ribbed plastic wad - again ok through full choke guns.
Sabot Slugs, are for rifled barrels - safe in smoothbores but will tumble.
Full Bore, Hard Cast, Heat Treated maximum penetration slugs, such as those manufactured by Dixie Slugs, are restricted to rifled barrels and in some specific cases to smooth cylinder bore (.730) barrels . Do Not fire any Full Bore Hard Cast slug through a choke constricted barrel.
Soft lead foster style shotgun slugs will flatten out or fragment on impact and seldom give the penetration needed on on larger/tougher game.
Small buckshot, such as 000B (.345 - .350"), as commercially loaded can safely be fired through extra full chokes without problems. Depending on the load modified to full chokes deliver the tightest patterns.
Large buckshot ammo: Dixie 12 gauge Tri-Ball loads contain three .60 caliber hard cast pellets with buffer in a steel shot type wad. These are safe down to .660 chokes, but pattern best from improved modified (nominal .705) to extra full ( .675 - .680) chokes.