This Remington manufactured late variation 26" plain barrel with a factory improved cylinder choke is for the Sportsman 48 semi-auto shotgun in 16 gauge with a serial number above 3,509,500. This barrel is in very good condition retaining the mojority of its thinning original blue finish blending with a brown patina and having a few spots of rust.  (file photos)

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

16 Gauge: 3541593