Do not remove the a2 fsb IMO.
Simply change out the magpul guards for a VLTOR CASV-EL drop in free float rail that will give you your extended hand purchase area, free floating, and absolutely no modification.
I have and use the CASV-S and it is a great product. Rigid and completely free of crap, err rails, unless you install them yourself, wherever you want them.
Caveat: Your magpul rear folding buis will either need to be filed a bit to fit behind the casv-el, or replaced for a Troy rear folding buis (which are also fantastic quality sights).
ETA LINK:
http://www.vltor.com/casv-sub.htm
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