No I haven't loaded any myself, because smoothbore slugs require a hollow base to make they fly reasonably true. I've made quite a few for rifled bores, and to my surprise a customer called a few days ago and told me that he loaded a heavy 50 caliber handgun cast bullet in shot cups with excellent accuracy out to 200 yards, and this in a smooth bore. Perhaps the LFN nose of his bullet provided enough form stability to keep them on coarse. I'm not recommending it though, unless you happen to have a 50 cal mold and shot cups which will handle them.
Surprisingly, I've made several 410 bore slug molds, but have never received any feed back, though I asked for it when I shipped the molds. Seems that many people who use 410 slugs on deer are convinced they are more powerful than the charts would indicate. Dead deer being what convinces them, of coarse!