unless you're looking to do an as- issued build ( which you can't do as the 14 is prohibited atm) you DON'T want one- the original clamps to the gas cylinder and shifts the barrel when you "go prone" ie shifts the zero- now that said, if we're dealing with the Chinese( and we probably are) the one offered by norinco is about as close as you can get to the original- don't forget you also need the e2 compensator along with a fake "fun switch" ( fire selector) if u use the usgi stock- now, a lot of guys drill out one of the rivets and mount a sling stud in there and put on a harris or equivalent- this mounts to the stock and DOESN'T SHIFT ZERO when u go prone- one of the ways u can tell an original is it should be stamped m2 and possibly have the feet re- welded in yellow- I have what I thought was an original that I got from springfield armory ( us bipod m2) and turns out it's a fake from tiawan- and belive me if I can get took, u can too-