Hi Treebeard. The Cimarron Ubertis went to the coil hand spring "around" 1999. They were advertising then so maybe a little before that. They called it (and still do) the Cowboy Comp Action. Some years later Uberti started doing it to all Cattlemen, but I couldn't tell you when.
I believe that when Pietta started making SAA repros (first were the GWII I think? Unless they made earlier ones in Europe) they used coils from the get-go. Need to confirm that with someone who has an early GWII.