What is the year of manufacture for a Remington Sportsman 48 16 gauge serial number 3521576?

The Remington Sportsman 48 was produced between 1949 and 1963. To determine the specific year of manufacture for a shotgun with serial number 3521576, you would refer to Remington's serial number charts. Based on the serial number provided, it is likely manufactured in the early 1950s, around 1951. However, for precise dating, consulting a detailed Remington reference or contacting a gunsmith with access to manufacturer records would be advisable.