I have mentioned this in other threads and never get a single responce.
I have a Colt Armorer/Depot Maintenance and repair manual. Second edition - 1991 for M16A2 rifles and carbines. Colt manual no. CM102 2nd edition - Rev A.95.
In this manual there is a picture of an A2 with a "C7" style upper but it is refered to as a "M16A2 rifle with field sight" (A1 style sight). Anyone ever hear that term or that model before?
It also depicts the "M16A2 commando" with that style of upper.

Yes, and that is the proper term for the so-called "C7" upper.

The C7 is a specific variant of the M16A2 developed for the Canadian military, who requested field sights, rather than target sights on their weapons.

Many variants used A2/FS uppers, including many of 7xx-series M16A2 Carbines, and some A2/FS uppers were also used for arsenal repair of M16A1s.  

~Augee

There is a thread in the retro forum where DPMS announced they had "A1" uppers for sale and everybody blasted them and said they are "C7" uppers and how they are "not correct". Well I guess they are correct, but not as an "A1". Some one in that thread also said they were correct for an "E1" he refered to as a "late A1". I don't know. I just dig the A1 sight. People can't fuck with your sights.

FWIW, in 2006 I was at Ft. Dix  NJ for the Warrior Leader's Course (formerly known as PLDC, or NCO academy) and I shit you not, I had a rifle issued there that by all accounts should never have existed--an M16A1 rifle with:

The early buttstock with rubber buttpad--I *think* used mainly on the first M16 (not A1);

Shiny triangular handguards;

Teardrop forward assist;

A1 pistol grip;

A1 birdcage flash hider;

oh--and an upper receiver with A1 sights AND a BRASS DEFLECTOR

If I hadn't had one issued and seen it with my own eyes I wouldn't have believed it either, but there is *at least* one out there like that. Man I wish I could've taken that rifle home with me, it was beautiful! It's probably still there...

I reckon this means I will have to build another rifle or 3.