eastbank said
is this a factory carbine.  

Yes it is.  It is what I refer to as a “Transitional” Carbine.  S/N 1112618 was manufactured in August, 1936 per the factory records.

The Transitional Carbines were introduced in May, 1932, and production of this variant ran through May, 1937.  The serial number range I have found them in is 1082935 – 1129740. In early June 1937, Winchester discontinued the old style Carbine butt stock & plate, replacing them with a non-fluted Model 55 butt stock & serrated steel butt plate. Thus far, I have documented nearly (400) of them in my research survey.