I've done it all the ways mentioned & they all work, just depends on your end objective & whether you want a real free-floated handguard & whether you want a short one, as you have, or a longer one. I distinctly prefer longer & floated.
So, IMO, & for my tastes, what Yondering suggests is the best answer................but the others all work too.
UTG also makes some more use-able & cheaper drop-in, 2 pc rails as well & those all more or less equal what you have with just a different look.
MM
