Hmmm - that is odd - I have the 50778 which is the standard 590 6+1 and had the plain plastic corn cob when I bought it - the 50776 model is the same barrel and capacity but is heavy walled barrel, A1 model with metal safety and trigger group, and it comes with the tri-rail forend
My only inclination is to say there was a shortage of plain forends and Mossberg sent out on that model? OR - they are making a running change and now equip the 50778 model with a tri-rail forend as well from factory (a good thing, if so) - Says yours was built on 3/18/??? (I can't see the year on the sticker on the box) - I believe I picked up my 50778 about a year ago so if yours was made in March of this year maybe now it has a new forend.
