If I wanted to buy a 10.5" barrel off of EE, do I need to have the paperwork in hand?  Once I have the paperwork can I put it on the lower reciever that I already have or do I have to have a designated lower?  Can you fill out the apprpriate SBR paperwork online or do you have to go a gun shop?
Any help is appreciated
Thanks

lol you need to go to the NFA forum and read up on how to get a tax stamp for an SBR lower...a little more to it then going on line or the gun store...

There is nothing that says you can't buy the barrel right now, or even put it on an upper. If you have a stripped lower already though you run the risk of it being intent to commit when you have a complete upper and lower even though they are separated. That risk is up to you.

Here's the general class 3 section:
http://www.ar15.com/forums/forum.html?b=6&f=17

In short...apply for your tax stamp on a Form 1 with exisiting lower sent to the ATF with $200 check. Wait several weeks to a few months to be approved. Once approved buy your short upper & you can legally install it on your newly registered SBR lower. You can also install a short upper on a pistol lower if you have one & still be able to Form 1 it for SBR. Pretty simple but the wait times get to a lot of applicants. Go to the class III forums for a detailed explanation of this procedure. First, however, make sure owning a SBR or pistol is legal in your AO.