Can this be done?

[Orca1_9904]

I was wondering, would it be possible to mount an M203 grenade launcher on an Armalite AR-10-series rifle or carbine? That way you had the stopping power and longer range of the 7.62x51mm NATO round and the anti-materiel capability of the M203 all in one package. Just a random thought I had. While we're on the subject, is it possible to convert an AR-10 to auto or burst mode like with an AR-15?