PART IV. Die Errors:

Cuds: 

Circumferential Cuds

Definition: A circumferential, or 360 degree cud, occurs when the entire perimeter of the working face of a die breaks away.  This can occur incrementally, as chunks of the die break off at different times.  A circumferential cud is thought to occur when the outside of the die neck is unusually brittle and when there is a sharp transition zone between the brittle exterior and a softer interior.

Circumferential cuds are extremely rare and are unknown among U.S. coins.  A few examples are known from other countries.

This 1918 Serbian 20 para shows a 355 degree cud