Graybeard has cited the very reason that a revoving cylinder rifle, with the attendant barrel-cylinder gap is fundamentally a bad idea. One from FA is not going to happen.
FA does have in the unannounced prototype stage, a single shot handgun (!). If manufactured, it might also be introduced as a rifle at some point. The prototype as I understand it is in 6.5 JDJ, with additional barrels in .357 Mag. and .375 Win. Several friends have shot the prototype.