That, my friend, is the first I've ever seen. I saw a trapdoor once and it had an 1896 Kragicon sight on it. Your Krag is the first time I've seen a Krag with a trapdoor sight. Not completely though. It's an 1877 trapdoor sight mounted on a Krag 1896 base. That is perhaps one of the strangest things I've seen on a Krag.

Stock is later than gun. I'd wager there are holes under that buttplate as only the 1892 stocks didn't have them and that isn't an 1892. Not unless somebody discovered a magical method of beefing up the wrist in a way I can't detect. Very unlikely.

Swapping out those 1877 bits for 1896 bits would help that gun greatly.

All in all that's actually not a bad gun. Not bad at all.