Go to the Remington Society of America and click the Manufactured link, it has the location and barrel codes for month/year of manufacture.
The Remington Wingmaster with the serial number 2039814 was manufactured in 1980. Remington's serial number system can help date their shotguns, and this particular number falls within the range indicating production during that year.
100-350 USD
Made by the Remigton Firearms Company.
Serial 718943w
The W ahead of the serial number indicates that your Remington 870 wingmaster was made in 1972.
Check this table for the answer: http://www.remingtonsociety.com/rsa/questions/barrelcodes
They are all still made in Illion, New York, I believe.
Do a search on barrel codes, I believe that will give you an answer
Look at the date code stamp on the barrel, see related link.
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.
Remington Society barrel code lookup: http://remingtonsociety.com/rsa/questions/barrelcodes
http://remingtonsociety.com/rsa/questions/barrelcodes