I have seen K98kicon rifles modified for a bottom sling before but NEVER one like that. If it were mine, I would remove the rear swivel and fill in the nail holes - at least it was not inlet for a swivel base, that is a plus. Then I would get a hammer and block of wood, and see if I could return the rear band to its original shape. I would try REAL HARD if the numbers on the band were matching.