I recently took a gamble on a police trade in Colt 6520. When I bought it, it came out of a large lot of 6520's in various conditions - this one came spray painted green with a thick layer of paint over the entire gun, but I picked it up for cheap online.
I disassembled the entire rifle and spent a few hours scrubbing it with paint thinner and a toothbrush and could not be happier with the results. Here it is:
The rifle seems to have been in excellent condition under the paint and cleaned up phenomenally. The exterior of the paint was pretty dinged up, so I think that it was spray painted when new and the pain layer actually served to protect the original finish underneath.
I called Colt and the serial number dates it to December of 1996. Barrel is dated May 1996, and the bolt is stamped MPLC which dates it to July of 1996. I guess that Colt used up parts made a few months before the "ship date" on their guns which explains why the barrel and bolt are a few months older than the receiver's serial number indicates. The upper receiver is also stamped "C MB" which is nice - the later production 6520's seem to often lack the "C" forge code.
The rifle is a ban-era gun with the "RESTRICTED" markings on the right side of the receiver and the small-diameter, screw-type front pivot pin with no channel drilled for the pin plunger. It also has the classic Colt grey anodizing which is very nice.
The only issue with the rifle is that the front sight post is destroyed from the previous owner trying to adjust it with pliers (I have another thread going on identifying the proper front sight post to replace it with). Other than that, the rifle is a joy to shoot - extremely lightweight and easy to carry, yet pleasant to shoot.