Rolling, Wrapping, and Crimping Machine Damage
So we probably average about one damaged coin like this a week on the forum. They are damaged by rolling, wrapping, and roll crimping machines.
The coins are damaged when the crimper fingers touch the end coin while spinning to crimp the ends of the roll shut. They can be found with partial circles and full circles depending on the pressure exerted on the coin. Roll hunters find them all the time, but people also find them in their change a lot because the bank coin suppliers use automation to wrap their coins.
Some Samples of Wrapping / Rolling Machine Damage
Click images to enlarge.