Now that the ban has expired, I was thinking of building a AR pistol.  My understanding was that you couldn't build one previously because of weight restrictions and handguard restrictions.  That said, I'd like to build build up something.  What would be legal?  What barrel length would you choose?  How would you go about getting a lower recieved registered as a pistol?  What kind of buffer tube would you put in it?

Thanks for any advice/help.

Rockclimbg

P.S.  I live in PA........I'm not sure if that makes a difference in terms of what is legal and what isn't?  I tried searching the ATF web sight for legalities but there isn't much info on this subject that I could find.....has anyone else found resources?