Originally Posted by sniper762
a free floating handguard has its own barrel nut incorperated within
Not all have their own proprietary barrel nut, some do. Some utilize the existing mil spec barrel nut.
OP, I would definitely get an upper vise block. Coming from a guy who many years ago trashed an upper receiver thinking I would out smart it.... Get an upper vise block or take it to a competent gun smith.