I purchased a Ruger Old Army that had been left loaded and in a drawer (probably most of its life). Two of the nipples would not budge to the point of "rounding" the nipples and wrench. I finally had to Dremmel a slot in the remainder of the nipples and use a hammer-activated handheld impact wrench to remove them. That was followed by chasing the threads on all of the cylinders with the appropriate tap to clean away the rust and crud. Came out like brand-new. I would be willing to try to work on yours, but no guarantees (expressed or implied).