Mark,

Welcome to the wonderful world of Krags and the Krag Collector's Association!

You have an interesting variation on the 1899 Krag carbine cartouche. Frank Mallory's reference The Krag Rifle Story states that the Block lettered JSA initials ( which represent the firearm inspector J S Adams) was used on Krag 1899 carbines. It appears that your JSA block letters were placed over the script JSA which were placed on all Krag rifle and carbine stocks made from June 1894 through the end of production in 1904.

If your stock was an early production 1899 carbine, there may have just been an error in putting the wrong cartouche on initially and then added the block lettered JSA over top. It could also have been an earlier carbine stock already stamped that had the block letters added when the 1899 carbine was initially built.

When the stocks were replaced after initial military use, the Springfield arsenal would not have added any further cartouches. They are only placed on the stock when first built.

So, we need more expert opinions on your carbine.
It would help to know the serial number of your carbine and we'd love to see more pictures if you have them.

Good luck and enjoy!