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Check the barrel date codes. They will tell you the month and year it was made. The serial numbers aren't entirely reliable.
http://www.remingtonsociety.com/rsa/que ... arrelcodes
It was probably earlier than mid-1965. I have two from November 1965 with serial numbers about 30,000 higher than yours. I have no idea what their production numbers were per month or per year.
Den
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