Both the 2nd Gens and Sig series were made from parts supplied by Uberti, ASM, and American manufacturers. But, Primarily Uberti.
There were a few (very few) fluted 1st Model Dragoons made in 1848/49. Page 55 'A History of the Colt Revolver' by Charles T. Haven & Frank A Belden; William Morrow & CO - New York 1940
Fingers (Show Me MO smoke) McGee - AKA Man of Many Colts - Alter ego of Diabolical Ken; SASS Regulator 28564-L-TG; Rangemaster and stage writer extraordinaire; Frontiersman, Pistoleer, NRA Endowment Life, NMLRA, SAF, CCRKBA, STORM 327, SV115; Charter member, Central Ozarks Western Shooters
Cynic: A blackguard whose faulty vision see things as they are, not as they should be. Ambrose Bierce