"Fraternal Organization Parade Rifle" or "Color Guard Rifle" is what I would call it.

IMHO - It blurs things to casually call this nickel plated Krag a "School Rifle".
(Although, it could have been 'spiffyed up' for an educational establishment's Marching Band/Color Guard).

I prefer to narrowly use the term, "School Rifle", for the official armory/arsenal 'altered carbines adapted for sling and bayonet'.