Today I received Change 6 to TM 9-1005-319-23&P on the M16A2 Rifle and the M4 and M4A1 carbine. It also addresses two other rifles, the M16A3 and M16A4. The M16A3 is apparently just like the A2 except it is capable of full auto fire. The M16A4 is just like the A2 except that it has a flattop upper with removable carry handle, it's 3 round burst only. I have seen both weapons mentioned in official publications (including a blurb in an old Infantry magazine that said the A3 was a flattop).
Has anyone (Michael, Gary) actually seen one, or know who they have been fielded too. I thought this was interestng since we've had a seperate thread for the past few days on burst and full auto.