Unless you live in a state that retains the AWB provisions, eg New Jersey, there is no longer any relevance to being pre-ban, the AWB law sunset in 2004. You can add any type of accessory you want so long as it doesn't cross the NFA threshold...suppressors, short barrels, etc. Even then all you need is the proper stamp and $200.
"The whole of the Bill (of Rights) is a declaration of the right of the people at large or considered as individuals.... It establishes some rights of the individual as unalienable and which consequently, no majority has a right to deprive them of." (Albert Gallatin of the New York Historical Society, October 7, 1789)
"A free people ought not only to be armed and disciplined, but they should have sufficient arms and ammunition to maintain a status of independence from any who might attempt to abuse them, which would include their own government." - George Washington