I doubt that the foster slug will hit the target where you expect it... but if you can keep track of where it would go, why not. A bead sight set for shot is a different beast from slug sights. Buckshot, well, it works fine at closer range. I say it should go in cylinder bore or improved cylinder. It does not take to shaping from a choke like a tall column of birdshot. It behaves more like smoothbore musket ball in flight. But what the heck. Try it and see what it does for you.