Go here and get this instead of a Pietta or Uberti. Get some Treso nipples for original Colts (made for #11 caps but my #10 Remington caps fit better) and you'll be good to go. If you have questions call Lodgewood - great people who know old iron.
1860 Army Colt Cylinder (Reproduction for Original)-#33 No engraving on the cylinder and no nipples included.
Some Uberti 1861 Navy cylinders fit original 1861 Navy arbors/frames, but it's likely to hit and miss, and miss again with production over the years, especially with the 1860 Army because of all the variants. The Lodgewood cylinder will fit.