You are lucky to own that rifle ,evidently BSA they only made 257 rifles between 1958 and 1967 ,the 458s were Prefixed with 9C ,i believe .i think the NC means Nitro Cellulose ,A fellow in Africa called Paul Grobler used for of them to shoot many [thousand ] elephants ,during 30 years of hunting with them ,and apparently the rifles never let him down ,despite being a maligned push feed ,does yours have the muzzle brake ? Im sure its a Majestic, as its the only Model thay made in 458.I would hang on to it if i were you !