PART VI. Striking Errors:

Off Center Strikes:

Uniface

Definition: An off-center strike in which the coin is struck against an underlying or overlying planchet.  The second situation happens less often.  In either case, the face struck against the planchet is featureless; the opposite face is die-struck.  In an off-center uniface strike, the entire face must be featureless.  If any of it is die-struck, it is designated an off-center strike with indent.

Due to the double thickness involved in such an error, effective striking pressure is elevated.  This often produces a “stretch strike” — a coin with an expanded “slide zone”.