What is the age of a Remington 870 Wingmaster with a matte finish serial number t502913x and barrel code only marked 50?

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 the serial number. You read off your serial number and the guy looks up in the database the year the gun was made and what the orginial barrel was for that gun.