Well, if I didn't know anything about guns and heard that phrase I might be for a ban too. It sounds scary.
It's a made-up term, Charlie. Invented to scare people. There has never been a gun called "semiautomatic assault weapon" until liberal Democrats focus-grouped what words they could make up to sound scary. It has no meaning, except in its strange definition in the actual Assault Weapons Bill.
Compare: For those who think Sarah Palin's answers often sound canned -- as I do, actually -- a bit of perspective.
Does Obama sound more comfortable? He should. He's been mouthing this gibberish for months, with lots of different chances to try out new ways to avoid saying the obvious. He has the memory of twenty or thirty variations on this balderdash to play with, mix and match 'em, make it sound fresh.
Hey, give Palin time. I'm sure she'll prove as capable of mouthing smooth nonsense as The One, if she needs to.