I'm bumping this one up because I have an 870 that was a new model for 2009 (gunmetal grey powercoated Tactical, that finish was complete and utter shit BTW, it literally peeled off in sheets), with an AB serial number prefix, and the barrel has a June 1994 date code.
Just to highlight why using the two letter barrel date code is not a really good idea when dating when the gun was made.
As to the fact that Battlefield Las Vegas claims the 870 has a short lifespan because a known wear part (ejector spring) wears and breaks after many thousands of rounds, don't even bother trying to replace (or have a gunsmith replace) that known wear part, and simply scraps that 870 and goes around calling the 870 a consumable... that's just beyond retarded honestly. Do we scrap an AR15 every time an extractor or cam pin wears out?
That 2009 870 I have broke the ejector spring after well over 10 000 rounds last year or the year before, the spring wore down at the ejecting claw that rubs on the bolt and finally broke when there wasn't enough metal left to keep it rigid. When that happenned, I took some cable cutters, snapped the spring off in half, tucked the remaining riveted part in the ejector cavity, and the gun ejects fine without the spring...