[Nervous Tick]

Bet you’re right about the rifling. I don’t have any experience with a rifled shotgun barrel.

At least slugs for rifled 12ga are readily available — I know because I continually trip on ‘em on the shelf while looking for smoothbore slugs. They’re pricy though.

[Paladin2]

"Good news!!! We have figured out how to load .50BMG bullets into 12 gauge hulls!!! By using a variation of our patented MassForward technology we are able to make the .50BMG round nearly three and a half inches long when the slug exits the barrel. In plain English a portion of the wad stays with the bullet in flight, like fletching on an arrow. Not everyone can own a .50BMG but now everyone who owns a 12 gauge can throw .50BMG rounds down range. This round is loaded with the M17 Tracer and will burn for 3-4 seconds. We have printed 10″ groups at 125 yards out of a 19″ slug barrel, and had the projectile burn out to 400 Yards"

I don't think they go too fast though.

[Beagle8U]

The Brenneke slugs will work fine for either smooth or rifled bore shotguns.