I recently purchased a knoxx Blackhawk SpecOps NRS Shotgun Stock. To start I was surprised that it came with the forend however it did not fit my mossberg 500. I gave them a call and they are sending me a new one free of charge. He said for some reason mossberg sells two different length action tubes and I had the shorter 6.5". I'm sure most know about the tube lengths but if anyone was hesitant on buying the knoxx stock they'll trade it out for you.