On some of the early rifles the SN was stamped on the underside of the receiver on the 'bevel' that you will see is a slightly rough, un-machined area, the same area in which the barrel locking screw is located, but on the other side.

Your "19" photo is too closely cropped to get a sense of whether it is of the number I am referring to. Do you have a wider photo of the area?

There are people stateside who would be interested in what you have I'm sure. Welcome to Ross Rifle is a place you could find further info.
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