What you own is a model R6601. Manufactured in the early 90's it went thru several evolutions. Yours being one of the early versions. Great weapon but due to the Kali law's of 89 that prevented Colt for being able to compete on an open playing field, they had to adapt. And they did. 'cuase you got one. Dropping 2 letters and 2 numbers allowed them to start reselling to the Kali klan again. But with some really dumb additions. Or should I say "Ommisions"?