Austrian made steel ersatz scabbard for a captured Russian M 1891 socket bayonet.(ABCN 817-a)

Austrian captured Russian M 1891 Mosin-Nagant rifle. Austrian made blued steel scabbard with an Austrian style frog stud and ball finial.(ABCN817-a)

During WWI, Austria and Germany captured a great many Russian Mosin Nagant rifles and socket bayonets. Be course the Russians did not make scabbards with their socket bayonets, (the bayonets were permanent fixed to the rifles), Austrians and Germans made their own ersatz scabbards. 
This bayonet is typical Austrian captured and can be told by its Austrian style frog stud of the scabbard. 

Total length: 445 mm.