The only Colts I am aware of that shipped with cases are some of the limited (few hundred) semi-auto special runs in late 1980s and 1990s. They used various zipper cases and shipped inside a brown shipping carton with label slapped on the outside. While I may not have seen every last one, this case does not ring a bell. My somewhat educated guess would be that’s it’s just an aftermarket accessory. A quick internet search yielded a few identical ones for sale right now in the $50 ballpark.