ColtFever.com says: In the mid-1980's Colt was undergoing a long strike and didn't have enough workers qualified to do the polishing on the entire Colt line. So, as a means of maintaining production Colt offered a series of revolvers with an unpolished flat matte black blued finish.
The flat black Detective Special was called the Colt Commando Special. It was made from 1984 to 1986. As soon as the strike ended the unpolished models were all dropped.