Interesting look. Note the rim cud is present, then the rim disappears partway around the rim on both sides. It looks like the metal filled the void, (the missing gutter area) then didn't have enough metal for the rest of the normal rim area. Thus the tapering area on each side of the rim cud. Never noticed this before, but maybe because the rim cud was so large, this happened that way. And on other rim cuds they are smaller and less metal is not lost filling the void and would have enough to create the normal rim.
What causes a rim cud? It is from the die, on the area on the outside edge that forms the coins rim. This I refer to as a gutter, is stepped down slightly from the fields. This allows the rim to higher than the coin, protecting the coin devices. When part of the gutter breaks away off the die, it leaves a void on the die. Well as know, when a void in on the die, it will leave a raised area on the coins struck by that die. What does this breakaway look like on the die. Well I simulated what it will look like on the image on the lower left:
That is what causes the rim cud to happen. Hope this helps a bit more. If we keep moving forward, at these are are going somewhere.