Almost like we are looking at 2 different receivers. The last photo looks like they forgot an operation. Going back and looking at BR's photo the milling operation around the trigger recess was forgotten. That may make what appears to be a step. I am not familiar with all the changes to the receivers between 1892 and 1898. But that "lost operation" would have made fitting a rifle stock a custom operation. Maybe the arsenal did not want to mess with it but a surplus seller might do the work to salvage a receiver.