I've not seen a two piece that was worth much, especially of you are going to hang optics or a front backup sight on it. If you have a front sight / gas block all in one then you will need to do some work to get it off. Google and a dremel tool are your friends. If you decide to do this, get a free float and a new gas block, then put a front sight on top of the gas block. I think Palmetto State Armory has some YHM free float rigs that are reasonable priced. You'll need a barrel wrench too - borrow or buy - they aren't very expensive.