I was surprised when I saw this post. I had never seen the case listed as a 22-15 SS. I thought this was something similar to the 25-20 SS. When I saw the pictures it was obviously the 22-15-60. I first became aware of the case when it was on the cover of Cartridges of the World (around the 3rd edition I believe). This was 60 years ago when I was a freshman in college. It was pictured in a group of cartridges and was one of the freakiest looking cartridge I had ever seen. It had an aspect ratio of over 8:1. Even at that time it was obselete. The writeup pretty much wrote it off as fouling faster than you could clean it. It has always been my understanding that the whole range of the 22 centerfires (and this one in particular) were supplanted by the 25-20 style of cartridges for small bore target shooting.In spite of this, I would still like to own one.
Like others, I believe that Rocky Mountain makes the cases. I have bought a lot of their products, mostly for old shotguns and black powder. At the pressures they run, their cases with BP simply last forever and are a good investment for antique guns. You only need as many as you would need at one sitting. With most bench or target shooting, reloading between targets is generally practical and actually preferred for changing conditions. Modern benchresters tend to firesort cases and have a match set that are fireformed and indexed fir rotation, using only these matched cases for sighters and scoring shots. With this system only a box of cartridges would be need for a match. I have never done BP target shooting but I thought at it's zenith, the bullet was started with a dedicated tool and a single cartridge used for every shot.
