On  the repros i have seen some are not the correct length and cover more of the receiver ring than they should. The Rivets holding the clips are not correct on some. A repro generally looks too good if that makes sense. Originals in many cases are not perfect. The Clips themselves can be wrong. In the Poyer book and others they show what identifies a correct hand guard for a given model. There are many variations.  Pictures would probably help the actual experts on here to identify it for you. I am very new to the Krag so i am not an expert but i do own a 1899 carbine that came to me with a repro hand guard.