The are not very common, but they can be found, so I'd say they are not rare. They are specific to the No 3. Each caliber had the same barrel profile - the same rings fit everything from 22 Hornet to 45-70. I've had a few sets over the years and I ended up selling them because with the ring and the base they are so top heavy, I feel they spoil the balance of the carbine. I have the aluminum Weaver base and the two part aluminum and steel Weaver rings on mine. It was the lightest combination I could find. I wish Talley made a lightweight one piece ring/base for this application.