In case "Inquiring Minds Want To Know ... ":

'Olderthansome' hit the nail on the head.

I woke up this morning considering the same idea of using a 'Trapdoor' butt-plate screw, as a replacement large screw, on an early Krag stock with a 'flat' butt-plate.

I took a 'Trapdoor' Springfield and tried its butt-plate screws, (they are both the same), on a model 1898 Krag's butt-plate.
(I do not have a model 1892 Krag to try this with ... hint, hint)!

The 'counter-sink' on the 1898 Krag and '1873 Trapdoor' butt-plates is not quite identical. The 'oval-head' 1873 screws were a credible fit and might fit correctly on a model 1892 Krag 'magazine rifle'.

BTW - 1873 Springfield butt-plate screws are not hard to find on ebay. S&S Firearms has them for $12, a screw.

---