I have a 3391B was actually produced in early 1914. Your serial numbers higher so I'm guessing it was produced in 1914 instead of 1913. I also have a nickel-plated 380 that was produced in 1914 and it does indeed show The Savage Banner on the side of the slide. If I had my book so I can confirm your year manufacturer but I'm not at the right location at the moment.

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