Trying to create a mantrap in your firearms is a recipe for disaster. Don't do it! It's a good way to end up killing yourself or a friend. There are many, many other better alternatives available as others have noted.
Beyond the legal and safety concerns, it is DEEPLY IMMORAL to intentionally create ammunition designed to harm or kill the user. Once it's stolen you have no idea what will happen to it. It could be quickly sold to someone who has no idea of its history, and sold again, before some innocent person uses it. To my mind that would make you worse than the thief.