My understanding is that all Colt LE6920s now come with the .170 oversized FC pins, and have an unmilled web in the receiver identical to the MT6400C's receiver. My personal 6920, bought in 2005, certainly did, and was identical to the MT6400C I bought in 2004 except for the flash suppressor, telescoping stock (both of which I have now installed on the MT6400C), bayonet lug, and rollmarks. Could have been different in 1999, of course. My 6920 also came with a M-16 bolt carrier. Both are very nice rifles, but MT6400Cs seem kind of hard to come by these days.