I am just wondering. I'll have two 1871 Open Tops in .45 Colt for main match guns, but I am thinking of getting an R&D cylinder for my 1860 I have. That would be my back-up gun for matches. I shot one for an article about 10 years ago and liked it. Even though you have to take the barrel off to reload the cylinder, it still takes less dexterity than the tight fitting 1858s.
On a side note, I found reference to Springfield Armory doing an experimental 5 shot, two piece conversion cylinder for Army issue 1860s. I honestly forget what caliber it was, though.
Anyway, post some pics and feedback.
Thanks in advance