Based on the Mossberg 590, the Shockwave is a non NFA firearm with a 14″ heavy barrel.
Mossberg discovered that they could legally manufacture and sell this shotgun in most states, as long as the stock is not modified.
Check your local laws to find out if it is legal in your state.
While this may not be the best bird gun, the Shockwave is a great close quarters weapon.
See it in action with this video from Hickok45.