The chaps at G&P have sent me an email to let everyone know that the metal bodies for the M733 and M16A1 have now been released. Both packages weight 850g and include a new ejection port cover, metal hop-up set, hop up rubber, receiver pin set, uprated nozzle and new rear sight set.
Both these new bodies have been on their "coming soon" page for some time, and are still currently listed as being out of stock, but you can expect to see these products at your local retailer very shortly.