You will notice the year code repeats itself, but over 20 years difference, so even if it was used on the same model, in all likelihood sights or stocks would be different which would indicate the different date.
You will also notice the month code spelling out BLACKPOWDERX, this is a common code in the firearms industry.
They however continued to mark the date code on the end flap of the shipping box for shotgun barrels however.
They planned on using just the serial numbers to tell when the gun was manufactured.
This sleuthing is accomplished in part by first determining the years that your specific firearm was manufactured.
Or by using the factory date codes on the barrel of the firearm.
These codes are fairly simple and straightforward to read.
In the picture below, you will see an example from a newer Remington 597 rifle with a manufacturing date of April 2006.
You can use the serial number to quickly decipher the date by using the chart below.
To determine the date, you need to look for the letters stamped on the left side of the barrel. The next letter (possibly 2 letters) will give you the year code.