If it 'twas mine and I wanted a receiver sight I'd go with the Lyman 57SA. As Rory said, the factory letter from John won't tell you much during that era. The Lyman 57SA is as good as any and better than most if you like irons. In my experience the discontinued Winchester 150 grain Silvertips are simply explosive and well worth buying when you can find them. Not the most accurate as the average for all my rifles is about 2" at a hundred but that's well under minute of deer. Good to know that it smells right too.
