Metalstorm has made outlandish claims as to it's cyclic rate of fire, but they never say what the rate is after the last tube has run dry.
Who on God's green earth is going to hump enough ammo to keep up? Consider that the "ammo" consists of a rifled barrel of the correct bore size, filled to the top with powder and projectiles.
It is a solution looking for a problem. I expect that it costs more then a Claymore mine and once it's shot it's wad it anin't worth diddly squat.
Regards,
GtG