First I assume you are talking about Colt large front pivot uppers?
Some people refer to them as C7 uppers. After the Canadian rifle model with the
same features, A1 sights and the case deflector.
I do believe that the first experimental A2 models featured this style of upper.
They are less common than the SP1 (no forward assist) and later A2 models, but
not really rare. They are normally found on Sporter II models, also know as the
SP2. Some Sporter II uppers are the standard A1 without the deflector and later
models featured the deflector.
Even though they’re seen less often and fewer where made, they are not as
popular as the A2 and normally don’t sell for more than an A2 style. I’d say from
$175 to $225 complete less barrel.
All Colt large front pivot uppers are light to dark grey and not black.
To recap, the following style uppers were at one time on another offered on Colt
factory AR-15s with the large front pivot:
SP1 - Field sights No forward assist No case deflector.
SP2 - A1 style Forward assist and no deflector.
SP2 - A1 style Forward assist with deflector ( Sometimes called the C7 style)
A2 - All A2 features, found on several later Colt models.
Flat Top - Rare, found 6700 competition Hbars.
I will try and get some pics up.