Sounds like an XS Government Model. These were made only in '99, and were designed to go head-to-head with Kimber and Springfield in the "features" arena. It took the GM the rest of the way from "enhanced" to a gun with real semi-custom features. It should have a beavertail grip safety with a dorsal speed-bump, and an extended, ambi thumb safety? Wedge-shaped rear sight? Among Colt fans, the XS has already gained near-legendary status, as they are said to be some of the best pistols Colt has ever made. If you have an XS, and you paid only $550 for it, you have both a great gun and a great deal. I see used ones going for $700-$800.