Aha!!

The "Bowers" list is nearly total baloney, as presented!!!  A reader has to know a lot about Krags to unravel it. It should be withdrawn, or extensively revised - period. I will attempt to contact the webmaster, at some point in the future. No one can be an expert on everything - and I believe he meant well enough, but he should never have phrased things the way he did.

There are no different types/models/styles/versions of the M1899 Carbine - other than the use of different rear sights. For example, where "1901" occurs in the second long listing (the one in all caps) it refers to the model of rear sight. Of course, he doesn't bother to point that out, leading to questions such as yours.

The other URL was just a Google search, which will have some bad info and some good info - I didn't check anything there.

While it is probably the least correct of the Krag books, Poyer is well worth the $20 (or sometimes much less, used, at Amazon, etc.)