I have a Colt Sporter Target Model that I purchased some years ago (R6551). Would the lower receiver on this rifle be considered a Pre or Post Ban? If it is a Pre Ban can a Pre Ban upper be installed on it?

Thanks
MA6279

If the serial number falls in the pre-ban range, and it came with a flash suppressor/threaded muzzle and pistol grip, then yes, it's a pre-ban.

Many transition model uppers had the bayonet lugs shaved off, but still had a threaded muzzle and flash suppressor.

If your barrel's not threaded, and has no bayo lug, and you never put a preban upper on it before 9/13/94, or your serial number falls past the cutoff date for your Colt model, however, you can't legally do so now.

If it's a Colt Sporter Target with a serial number ST038100 or below it is a preban.  Call Colt and they will tell you over the phone the date it left the factory. For a fee they will document all the features in writing when it was manufactured.  A Colt with a three letter alpha serial number is postban.