Well, I don't know about never, but the 1858 was a steel-framed gun. They weren't made of brass because they didn't need to be - the North had no particular shortage of iron, so there was no need to substitute "inferior" metal.
One of the easiest ways to answer the question is to compare the number of original brass framed Remingtons to the number of original steel framed Remingtons. If brassers were common, you'd see them turn up here and there. Since they don't, it seems safe to say that there either weren't any made or there were so few made as to not really matter.
It seems to me that the whole brass-framed guns, the so-called "Confederate" guns, are, for the most part, an Italian invention. It's my opinion that they saw the Griswold and Gunnison as a copy of the Colt Navy and ran with the idea that anything brass framed was Confederate. There were plenty of steel and iron framed Confederate revolvers - and plenty of them were Colts. Sam was making revolvers well before the war started.