Okay I forgot to explain the picture link. I'm kind of absent minded about anything other than guns or cars, or sometimes women. Anyhow, the pic with the red background is an A2. I've circled the forward assist as well as the brass deflector. All of the blue background pics are of a Colt SP1 (aka civilian M-16 A1). Notice the absence of brass deflector and forward assist. The stamp on the left side of the weapon in the next pic shows that it is in fact an SP1. Finally, on the last pic you'll see a better view of the absence of said upgrades. I had another pic that showed the safe, single, full auto selector, but it was inconclusive unless you've actully used an M-16 and knew what it meant.
Okay, that all for now.