This Remington manufactured early variation 28" plain barrel with a factory full choke is for the Sportsman 48 semi-auto shotgun in 20 gauge with a serial number below 3,806,300. This barrel is in very good condition exhibiting a mixture of original blue finish with some thinning areas which are now a soft brownish gray patina.  (file photos)

Note: Remington Sportsman 48 semi-auto shotguns with the following gauge and serial numbers have been observed with this part:

20 Gauge: 3804965