Not a carbine expert.
The early carbines did not have a bayonet lug. The L shaped sight was preset for 100/ 300 yards, and was an attempt at economy. Winchester was ONE of the companies that made over 6 million of these for the US Military. There are all sorts of variations- high wood/low wood, flat bolt/ round bolt, sights, bayonet lugs, and even the full auto M2.
What year is marked on this one? Cannot recall Winchester ever making one for the civilian market. A few companies did- AFTER the war.