I'd generally shy away from the .410 for deer if you can. While it will certainly do the trick, it's somewhat on the low end of the power scale. If, however, you are on a limited budget, want a small-statured person to shoot it, or for some reason just WANT to, pretty much any of the slugs on the market will do. If you have a 3" chanber, Bismuth and Brenneke both make slugs. Remington and Winchester also stock less-powerful 2 1/2" slugs. I'd go with the Brenneke, but I don't have any personal experience with any .410 slug. They are about in the same class as a 357 magnum from a lever action IIRC. For deer, you might be better-off selcting a 3-pellet buckshot load. Depends on the size of the deer too. Understand that 1/4oz is only 110 grians. A 1/5oz is only 88 grains or so. We're looking at under 800 foot pounds of energy here. Still enough, of course, but I would prefer a clean kill on animals.