The original LWRC M6 was like that. It's since been discontinued and replaced by the M6-SL, which uses the midlength gas system and midlength Magpul MOE handguards.
Just take a standard DI, retrofit it with a Osprey Defense piston kit...It comes with a standard HG...I did one for a local PD...4500 rounds and they seem to love it...I have one on an M4, works great..