He's some pics of the last one of the 'Niedner' type buttplates I picked up at a gunshow some time back that I mentioned above.
They were lying out on a parts purveyors table among the Mosin Nagant trigger guards and SKS accessorys.
I just thought they were nice butt plates for custom projects no matter who made them so I bought the bunch.
The checkering is entirely uniform and sharp (without being painful!), not cast.
The edge border appears to me to have been milled out to the depth of the checkering.
I think these were done on flat stock already checkered by what ever means. The border milled to the correct outline (you can see milling marks or some sort of machining marks in the closeup pic), then the flat piece was formed to it's present shape.
On first look the screw holes look punched out with the flashing on the back side, but they are drilled and countersunk.
Just my guess of course. A lot easier than pounding one out of semi round stock and checkering it, but that is the way I heard it done too.
Maybe just copys made later for sale 'to the trade'.
I have no idea if these are Neidners or not but thought they might be interesting.