E192 - Imperial Russian Mosin-Nagant Model 1891. 
Socket bayonet for the Model 1891 Mosin-Nagant rifle. This example numbered 20961 (original issue barred out:  97263), made at the Tula arsenal. A good example of a Great War Russian bayonet with the locking ring (NOT the later 91/30 type with the spring catch) of early pre-World War One type, not normally found in this good condition.