I use these little jewels for any 12ga slug hunting I do (or, used to do...450b made that a lot less attractive.) They're Rio Royal MG fragmenting slugs (Bala Balinda)...they have a steel penetrator surrounded by a lead slug with "fins" that are designed to break off after impact. I don't know why these are not more widely known in the hog hunting community...they are quite amazing. Link is to a YouTube drywall/meat/gel block test. Take a look!
http://rioammo.com/law_enforcement/rio_ ... _slug.html
Able Ammo has them in stock: http://www.ableammo.com/catalog/royal-s ... n=ammoseek