Arsenal Rework Markings?

Hi all,

On the subject of the Mosin Nagant M91/30, I Was just wondering if anyone knows if all rifles that were reworked postwar had the markings on the reciever ring or not. It seems like almost all I have seen have the markings but I have seen a few without including one of my own. The rework markings I am talking about are small squares on the reciever ring with either one verticle line or an X inside. From what i understand one indicates metal rework and the other wood. Any ideas?

Thanks

Verticle line in a small box is metal rework, diagonal line in a bigger box is wood rework. Metal should be on metal, wood on wood usually on the butt end of the stock but these are sometimes sanded off or almost sanded off. Wouldn't surprise me if a lot got missed as most of the recent imports would have been reworked.