This Winchester manufactured 28" plain barrel with a fixed full choke and very good bore is for the model 12 slide action shotgun in 16 gauge with a 2 3/4" chamber. The overall external condition is very good retaining perhaps 50% of its thinning original blue finish with a few specks of light surface rust and honest wear.  (file photos)

Note: Winchester model 12 slide action shotguns with the following gauges and serial numbers have been observed with this part:

16 Gauge: 808640 & 1116030