PART VI. Striking Errors:
Broadstrike:
Centered
Definition: When a perfectly centered planchet is struck out-of-collar, it expands evenly in all directions. This error can be called a “centered broadstrike”. However, since the majority of broadstrikes are centered, hobbyists usually refer to it simply as a broadstrike. If the planchet is not well-centered, but the design remains complete on both faces, the error is called an “uncentered broadstrike”.
The failure of the collar to deploy and surround the planchet before the strike can conceivably arise from a number of circumstances and will vary depending on the press brand and model used. In the Bliss press, the collar rests on springs and remains in place while the anvil die rides up and down inside it. Debris trapped between collar and die shank can cause the collar to ride up and down with the anvil die, preventing it from occupying its normal position during the strike. While this scenario has not been proven, it is at least plausible.
The 1999-P Roosevelt dime shown above is a centered broadstrike
The 1999-P Jefferson nickel shown above is another centered broadstrike.