Yes, I realize this is a S&W forum but the expertise available here is too good to pass up! (How am I doing?)

I bought a used Winchester 77 recently. The seller advertised the rifle as original. When it arrived, I noticed a notch on the stock on the opposite side of the sliding safety. I don't remember such a notch from the first time a bought a 77 in about 1964. Additionally, all the pictures I've located through various sources have no such notch.

The interesting point is that the serial number is 1676 which makes it a very early gun. It could simply be a variant for a really early model or it could be a non-standard stock.

Any help would be appreciated! Thanks.

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