Probably got 150 rounds of assorted shells through my 14 inch 6 shot Mossberg. Two more of my shooters have theirs and many more rounds through theirs.
The paper work that comes with these guns stays with them at all times. What we noticed is the paperwork is dated October 2015. The paperwork is to Asylum Armory for their Gatekeeper model. Apparently, these folks were turning these things out before Mossberg ever thought of it.
When Mossberg had them at the Shot Show our local dealer said they were told they were covered up with orders.
Asylum Armory offers them with the Remington 870 for the same price. We all chose the Mossberg because you get 6 all up instead of 5. All ours are working perfect and all are riding in our vehicles. Paperwork in the glove box.