Any Krag carbine requires close scrutiny. Expect to pay $1,000, and up, for legitimate examples.

Basic warning flags are: 'Banded' front-sight, barrels not exactly 22" (measured from muzzle to closed bolt-face), presence of sling-swivels (always suspect), serial numbers outside known 'ranges', non-carbine rear-sight, atypical muzzle crown, stock tip with wood 'plug' and lacking barrel-band spring.

When sold off by the Government, lots of Krag rifles were cut down to make them more useful for Hunting.
"Quasi carbines" were cobbled together commercially by companies like Bannerman's and Stokes Kirk, when Krags were cheap and parts were abundant.
The presence of a carbine part(s) on a 'cut-down' rifle, does not make it a carbine. There seem to be a lot of individuals trying to get big money for a $300 cut-down Krag rifle.

Even buying a basic reference book, like Poyer's, "The American Krag Rifle and Carbine", for about $25, can help guide you in Krag purchases and increase your enjoyment.