Quoted:
Quoted:
He has a large hole lower with a small hole upper. It didn't come from Colt that way. The pin in there adapts the small hole upper to the large hole lower. He can't put the original Colt 2 piece screw in, it won't work. He has two different Colt rifles mated. I'm half asleep, so correct me if I'm wrong.
Actually, it might have come from Colt that way. There was a brief time when Colt had no more large hole uppers but some large hole lowers left over. However, the adapter pin on the subject rifle does not look like the type Colt used back then.
I doubt that you'll ever be able t establish for sure whether the thing was done at the factory or afterwards.
Sorry, Colt NEVER used the aftermarket adapters to put small hole uppers on large hole lowers. When they made the transition to small hole uppers and lowers it was done simultaneously. It was also done well after the mid 1980's when this rifle would have been produced. I can't tell by the photos above but the upper appears to have a keyhole forge code, one that would not have been used in the 1980's so the upper pictured would not have even existed when this rifle was made.
When Colt first introduced the AR15A2 Sporter II they came with all A2 furniture, an A2 government weight barrel with 1/7 twist, and a SLICKSIDE upper. The first upgrade Colt made was the addition of the forward assist. The button was a large round button that was cut flat on the interior. The next modification they made was the addition of the brass deflector.
Below is a photo of a factory AR15A2 Sporter II as it would have come from the factory in the mid 1980's.
It was the late 1980's, possibly 1988 or 1989 that Colt finally started using the large hole A2 uppers on the Sporter II. ALL of the uppers that had large front pivot pin holes had CM forge codes. Later forge codes were C MB.
At some point in the 1990's Colt transitioned to the A2 lowers but for some reason retained the large pivot pin for a short time.
It was around 1994 when Colt started using small hole uppers and lowers. However, they still did not use a captive pin as do M16's and all aftermarket AR15's. They instead chose to retain a proprietary pin similar to the SP1. It had a .250 pin that had no slot for the detent and it was threaded on the opposite end to accept a screw.
Colt finally transitioned to the captive push pin around the time that the company was renamed Colt's Defense.