I seem to remember, back a ways, (don't quote me, I can't remember breakfast yesterday) I remember both Cimarron and CZ offering their Hammer Doubles with a longer set of barrels. Either 26 or 28 inches. Don't remember which (see ... Memory shot) but there definitely were longer barrels offered.
Problem. Limited Market. Actually, almost no market. To produce something, in a quantity sufficient to produce profit, gotta have a market. Two or Three fans does not a market make. So, if an importer doesn't initially order sufficient quantity for a profitable run, there is no production. We saw the longer barrel Cimarron once. Just once. Not enough sales activity to justify doing it twice. Oh well.