The 16I barrels tamp is just the final assembler's stamp, meaning the person who put the rifle together at the factory. The "J-Series" that I think you're referring is something else all together. You will also find another stamp with SP inside a circle on the barrel (often on the under side just ahead of the barrel nut) which is the proof mark indicating it was proof tested at the factory (SP = Savage Proof).

Love that it's still in its factory original configuration after all these years. Definitely a keeper!