Fallout: New Vegas Deathclaw Bug?

I have a little issue. See, I'm trying to get Bloodborne Cave and FUN! There are deathclaws EVERYWHERE. So after killing most of them, the final deathclaw wasn't much of a problem. Except, even though his HP clearly has no bars left, he won't freakin' die. I'm using the Oh, Baby! and Veronica has the Ballistic Fist, what the hell is wrong?! I've used V.A.T.S, to no avail, tried different weapons, nothing. Rex just keeps getting knocked out too. Help me please?