Right now over on the Contemporary Longrifle Association site on Facebook, there are pictures posted of a mixed metal Tennessee rifle by JB Duggar & E Smith. Most all the furniture is brass, but the trigger guard is iron. It is a really beautiful rifle. Elisha Bull also mixed brass and iron in his rifles. I have pictures of one that I used as inspiration for one of my current builds. It has iron butt plate, toe plate, side plates, and trigger guard with the rest of the furniture (including patchbox) in brass. There is also a mixed metal Baxter Bean rifle on the covers of Randal Pierce's book "Kentucky Rifles of the Great Smoky Mountains." That one is another awesome rifle! In that same book is a John Bull rifle mounted all in iron except for the ramrod thimbles which are brass. They are out there, just have to dig for them!