Along with all the other democrats.
He didn't write the bill, push the bill to the floor, or talk to anyone about it. He didn't do anything beyond the bare minimum to tow the party line. Reagan is FAR more responsible for that AWB than he is.
I'm not saying he doesn't want a AWB, mind you. I'm sure he sees it as the sane and practical thing to do for the same reasons Reagan did, and is of the same (IMO wrong) line thought that no one needs "military grade" weapons - just as Justice Scalia was. It, however, is not something he's historically supported more than any other Democrat (and he has a LONG history of being in a position to do so), and further, isn't anything he can actually achieve as president. (And even if he could, it wouldn't be anything of the mass gun reclamation folks have been predicting - even if it still wouldn't be to my liking.)
Though I will give you his is among the least likely Democrats to tow the party line, so the fact that he's willing to here, is a bad sign. Nonetheless, he could be fucking Dianne Feinstein's twin with a dick, and still couldn't do dick as president - actually having more power in that department as a senior senator.
Granted, the far left harped on him for this exchange:>"You are actively trying to end our Second Amendment right and take away our guns," one man accused Biden.>"You're full of sh**," Biden snapped back. "I did not—no, no, shush. Shush. I support the Second Amendment."
...and has previously accused him of not being a gun control supporter, in that, and other Huffington post articles. In addition to harping on his previously strong support for border control, welfare reform, and the like.
He also voted against smart gun regulation, voted for the NRA backed Firearm Owner's Protection Act (FOPA), (which created the "gun show loophole") claiming "measure that saved gun ownership as we know it.", and he is a gun owner himself.