If the magazine cannot be inserted on a closed bolt, then it is not possible - physically - to load more than 3 rounds. Since that's what the law regulates, why would you think the magazine is illegal?
Now -- the question becomes, what if some inventor wannabe tries changing the spring or modifying the follower to allow it to be loaded on a closed bolt? Of course, then they have taken it upon themselves to violate Federal law -- but it still shouldn't invalidate Mike's original design.
Jim
Federal law only allows waterfowl hunting with a gun only capable of holding thr