That particular weapon is an H&K MP-5k, a 9mm. Similar weapons with folding stocks are available in .223, it takes about 3 seconds to snap on a scope.
I think everyone is being done a disservice with the "one lone white wacky gunman" theory or the "one lone white wacky gunman and his friend Earl who drives the truck" theory.
This could be a well financed, well thought out campaign to instill terror in our nations capital.
If that was their plan, they are succeeding.
I've heard supposedly bright people say, "If it was Al Queda, they would be taking credit". Why, so they would be easier to find and stop? The less people know about what is happening, the more terror. Isn't that what it's all about?
He still has a side weapon and possibly a few more tricks.
Hopefully, the cops would keep the dogs running so they don't lose the guy rather than everyone "concentrating" on the backpack.
Sac