With due respect for Oyeboten, there were two phases of Second Generation Colts, but the Signature Series was not a part of it. The two phases of the Second Generation were:
The "C" series which consisted of the M1851 Navy and the Third Model Dragoon. These guns were made from crude Uberti castings that were finished and assembled in the Hartford Factory, using American made internal parts and screws. The C series guns had a bright blue finish similar to that on SAA Colts; and the "F" Series which were made by Lou Imperato's Harrison and Richardson factory, under sub-contract in New Jersey. The F series consisted of all Hartford percussion models except the M1849 Pocket pistol. Production of all Second Generation Colts was abruptly terminated in 1981, and Lou Imperato lost Harrison and Richardson as a result.
The Signature Series came about as a settlement of lawsuits against Colt by Lou Imperato. He was granted a license to manufacture Colt percussion revolvers and the use of the Colt name and copyrights. He established a plant to assemble the Signature Series guns in Brooklyn, N.Y. under the name Colt Blackpowder, Inc. Lou Imperato was able to re-hire most of the people that worked in his New Jersey plant. The Signature Series consisted of all Hartford percussion models except the Roots, plus a Texas Paterson model having a 7 1/2 inch barrel and loading lever. Production was from 1995 through 2001. Colt had nothing to do with this series except for a few guns purchased by the Colt Custom Shop.
Since the Signature Series guns were assembled and finished by essentially the same people, many collectors call this the 3rd generation Colts. For more information about both 2nd generation and 3rd generation percussion Colts, I suggest getting a copy of "Percussion Colt Revolvers, the Second Generation, Collectors Handbook & Price Guide #6".