Check the Remington Society of America, date barrel codes and location.
http://remingtonsociety.com/rsa/questions/barrelcodes
See related link.
Serial 718943w
100-350 USD
http://remingtonsociety.com/rsa/questions/barrelcodes
Perfect condition, 28" BBl with Rem chokes, $350.00. Short rifle sighted slug BBl with no chokes $290.
Contact Remington Customer Service thru their website.
Made by the Remigton Firearms Company.
The W ahead of the serial number indicates that your Remington 870 wingmaster was made in 1972.
http://remingtonsociety.com/rsa/questions/barrelcodes
Check this table for the answer: http://www.remingtonsociety.com/rsa/questions/barrelcodes
It's date stamped see related links for info.
You can call Remington at 1-800-243-9700 and go thru the menu selection. One of the menu options is to request information on your Remington based off of the serial number.