If you are talking, as I believe you are, about a carbine with a short stock, the wood itself is almost certainly genuine, as the short grasping grooves would be nearly impossible for bubba to fake. Then you must compare the front sight to a genuine example. A visit to SRS will give you some idea of the 1896 carbine ranges. A few 1896 carbines were restocked with the long M1899 wood - they will not have the bar and ring. Serial number must be in range.

The 1898 carbine is a BAAAD situation. They originally had the short stock, but were almost immediately restocked, so look EXACTLY like a model 1899, except for the serial number, which should be between ABOUT 111000 and ABOUT 139000. The ONLY way to be SURE of an 1898 carbine is to have an SRS hit (UNLIKELY - they only have 152 of the 5000 numbers). The offical Springfield Armory website is almost useless for serial number information.

Only ONE sight, and HG fits the short stock, the 96C, which is so rare as a loose part, that genuine examples fetch over $700, AND they are being faked. Once the carbine gets into the long stock - ANY carbine sight and HG COULD conceiveably be correct.

The only model of Krag carbine that is relatively trouble-free is the Model 1899, which is so marked. The 1896 and 1898s are a minefield for the uneducated. The best thing to do is read the books, and examine as many genuine guns as you can.