Howdy Joe,

Well... your question could have several answers depending on a few things.  Which rear sight do you have?  Depending on whether your carbine has been through an arsenal rebuild/update, it could have one of a few different sights, and any of them would be correct.  All carbine rear sights are clearly marked as such, and are calibrated different than rifle rear sights (which makes some fakes easy to spot).  The 1896 sight has elevation only, while the 1898, 1901 or 1902 have windage and elevation.  If you go to the photo page on this site, you'll find some pictures which will identify the different rifle and carbine rear sights, and the correct associated hand guards.