This Winchester manufactured 26" plain barrel with a fixed modified choke and moderately pitted bore is for the model 12 slide action shotgun in 12 gauge with a 2 3/4" chamber. The overall external condition is very good retaining most of its 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:

12 Gauge: 588236