Check out
www.remingtonsociety.com If the barrel is the one that came on the gun you can look up the date codes to find when it was made. It is probably supposed to be a 28" barrel, but for some reason most of the Remingtons I have measured are slightly shorter than advertised. A few are longer. I suspect they make them all at least 30" long and cut them at the vent rib posts.
Looks like just a standard 1100 from the 70's. I had one just like it around 75 or 76.