i have a new 2009 remington 870 express with a slug barrel / bird barrel combo
this ghost loading crap dont work in that.. i tried it a few times and it seems that the bolt carrier hits the shell thats on the lifter
its a new gun and nto broken in yet
i call ghost loading crap because there is simply no real world need for it
hunting or tactical wise. its a trick and there is not a single reason why you'd want or need to float an extra shell and take the chance of jamming your gun ( bypassing the normal operation and function of your weapon is not very bright )
but having said that, maybe the mossbergs have different dimensions between the lifter and the bolt carrier and this trick is a bit more possible.