An old friend had one with a 4 digit serial # and no letters. It was a carbine also, and one of the most accurate rifles I've ever seen. It took some research to get loads that would shoot into one ragged hole at 100, but he did. Try new brass, go completely through all steps of case prep, and try IMR 4320. He shot Sierras, but yours might like something else. There is new brass for sale, and many good bullets available that weren't 35 years ago. Enjoy. CB.